Gold makes the World of Warcraft go around. This currency is needed in everything from purchasing basic equipment like food and water, repairing your gear after a hard day's adventure, and even buying trinkets and gizmos to have some fun. When World of Warcraft was first created there was no auction house. A player had to shout across a zone, "Selling X item, starting bid 2 silver!" then others would reply in kind raising or lowering the bid until it was sold. Blizzard has made many advancements for us in Azeroth and made it much easier to barter your wares with other players, they introduced the auction house.
An Overview
The auction houses in World of Warcraft are your one-stop-shop to bid, buyout, and even post your own items for sale and it is the easiest way to find gear or items you need either while leveling or playing end-game. Whether you are an alchemist making potions for profit, a blacksmith who finally crafted an amazing chest-piece, or just a lucky person who found a good quality item after slaying a vicious beast you will need an auction house at one point or another during your adventures in this vast wide world. Auction houses are conveniently located in any major city of your faction for the horde: Orgrimmar, Thunder Bluff, Undercity, and Silvermoon for the alliance: Stormwind, Ironforge, Darnassus, or The Exodar. If you can't find one just ask a town guard and they will point you in the right direction. There are also neutral auction houses located within Booty Bay, Gadgetzan, and Area 52; these are places where characters of the Alliance and Horde can barter items between one another.

The Art Of Buying Low And Selling High
There are many ways to make gold within the auction house and not the least of which is the art of buying low and selling high. This strategy can take a good deal of gold to invest but the returns are well worth it when you see your money coming back twice as much. When I was on a couple of days ago I noticed a Star of Elune with a 20 gold buyout. These usually sell for 42 gold or more depending on inflation and so I bought it, posted it for 42 gold buyout, and it sold in just a couple of hours.
A key part of this is knowing what items to buy and which one's you can usually make a return profit with. Safe bets are usually cloth pieces (Linen, wool, silk, mageweave, runecloth, netherweave...), some higher level gems (Talasite, Living Ruby, Star of Elune...), Ore (Copper, Tin, Iron, Silver, Gold, Mithril, Thorium...), and herbs (peacebloom, silverleaf, earthroot, mageroyal, wild steelbloom...) as these items are needed by the mass majority of players at almost any given time.
Before you start buying massive amounts of product make sure you watch your market with the desired items to see it's trends and notice low buyouts or bids you can turn a profit from. The economy in World of Warcraft varies server to server and day to day so either record your results or download the Auctioneer add-on and scan the auction house daily as Auctioneer notices market trends, can alert you to low buyout profitable items, and posts auctions at their most competitive and likely to sell prices by automatically filling in the bid and buyout spots when you place an item into the auction house.
Just remember to be careful as you can lose as much as you could gain.

Is The Deposit Worth It?
Sometimes you may think you just received a great item out of a chest or from loot, but sadly not everything is worth placing in the auction house and those items are referred to as vendor trash. If you placed the item in and it sold, you would still lose money from paying the deposit and for it selling so much lower than you would have recieved selling it to a vendor. Unless you can use it or have a friend or guild member that could; it is usually a good idea is just to sell them to a vendor and save yourself the hassle. It is always a good idea to check the current going prices and what a vendor will pay for the item before auctioning it off. You can also reference http://www.thottbot.com/or wow.allahkazam.com for the item and look at its value to see if it has hopes for coming up in price and just hold it in your bank if the gold isn't needed on the spot.
Here is a list of item qualities (the color of the item’s name) and if they should/should not be placed in the auction house:

Legendary and artifact equipment (Orange and Red quality) are as current Bound when Picked up and can not be auctioned but can be showed off by you if you are able to equip them and only a couple of these items even exist.
The above chart is true for virtually every item in World of Warcraft. Do keep in mind that certain items such as Light Feather can be auctioned because mage's and other classes need them to use certain spells and they usually sell well. Just keep an eye out and if you think other players could use an item, auction it, and if it doesn't sell there is always a vendor willing to give you copper, silver, or gold for whatever trash you bring his way. The only true exception to this is usually quest items as most are soulbound when you receive them.
Auctioneer
Auctioneer is an amazing add-on we mentioned earlier. If you are interested in obtaining this add-on please visit http://wow-en.curse-gaming.com/ for all of your add-on needs, check out the left hand navigation panel and click on the link for add-ons. This specific add-on, Auctioneer, is the most useful for the game, in my opinion, because it keeps a record of the market and posts your auctions accordingly. This process saves you time and in turn leaves more room open to make some serious gold.
Use Auctioneer to scan the auction house daily and record market trends so your auctions are accurately posted. When you are posting auctions make sure to set the time length to your own preference, the default setting is 24 hours which requires the largest deposit. Depending on the length of your auction the deposit will change, usually 8 hour auctions are your best bet and you should post auctions during or right before your server’s peak time. Peak time is simply when the most people are online such as the weekend or a weeknight. All of Auctioneers functions are used on your auction window that comes up after speaking with an auction house NPC; you will see added buttons with tooltips that explain their functions.

Auctioneer also has the ability to scan the auction house and point out items that are being sold far below recommended price which you can turn a profit from purchasing and reselling. After scanning the auction house you can mouse over an item to see its current values, this functionality is very useful when deciding what items to auction -

when you have limited funds to work with. This database also has vendor values it adds to an items tool-tip to better help you identify good buys and if the item is worth it’s deposit. This tooltip functionality automatically works all the time, even when looting an item.
If you download this add-on make sure you are clicking the link to download the correct version compatible with World of Warcraft’s current version ex. 4.0.1 (most current version of Auctioneer). Here is a link to where you may download Auctioneer. http://wow-en.curse-gaming.com/downloads/details/78/
Controlling The Market
Controlling the market and prices of specific items may need to be done at certain points during your servers lifespan and can greatly increase your profit margin. At certain points your market may crash on items that could make you a lot of gold. Stacks of Copper Ore selling for 30 silver? If so, then we will fix it! This may take a lot of gold to invest in but it is worth it and people all over your server will be thankful. It may also be better to team with friends while attempting to fix your server’s market.
This whole process is relatively easy, simply buy all of the selected item and re-post the auctions at a good price. If you need help with knowing a good price to post reference one of the sites indicated in the links section of this guide. After you start doing this people will start noticing your price and post theirs competitively and thus the market is fixed for the time being. Remember to do this with more than one character so you don’t look suspicious to your server’s population and may get reported. This is a necessary evil for when items like Primal Fire are selling for 2 gold each when it should be about 20 gold. Before you know it your auctions will start clearing and you will make a lot of gold and reap the advantages of future farming you may accomplish.
Cross Faction Funding
Have you ever wanted to start a character of the opposite faction, but don’t want to start out from scratch? Cross Faction Funding is your answer. This is a very simple technique using the neutral auction house to fund your other characters. To do this you need a friend whom you can trust and not someone who will steal your hard earned gold.

Simply create your new character of the desired faction and go to a neutral auction house located in either Gadgetzan or Booty Bay. Then put an item like your starting shirt into the neutral auction house with a buyout of your desired gold to transfer. Then Log onto your main character and transfer funds to a friend who will then go to the neutral auction house and buyout the item your new character put in. Now you’re done!
Remember, the auction house will take its cut out of the item you sold, so if an item’s buyout is 100 gold, you may only receive 80 gold. Make sure you also have a very trustworthy friend to help you as you can not buy items that the same account put up for auction. If you happen to have two accounts it makes this much easier as you can do it yourself and do not need a friend’s assistance. Last of all, have fun on your new and wealthy character!