The Diablo® III real-money auction house is now available in the Americas game region for the U.S. dollar, Australian dollar, and Mexican peso. With the real-money auction house, players will be able to buy and sell the loot they find in the game using actual currency via approved third-party payment services or using their Battle.net® Balance.
The real-money auction house for the Europe game region and the remaining Americas game region currencies (Chilean peso, Argentine peso, and Brazilian real) will launch in the near future. We are rolling out elements of the real-money auction house separately to ensure all of our players have the smoothest possible experience. We'll have more information on the availability of the European real-money auction house and the remaining Americas currencies soon
To access the real-money auction house, click on the "Auction House" button on the left-hand side of the campaign screen, and then on the button showing your region's currency in the upper right-hand corner of the auction house interface. This will switch you between the gold- and real-money auction houses. Latin American players will have access to trade using the United States dollar, Australia dollar and Mexican peso.
Currently, the maximum bid and buyout that can be set on any one item is $250, and there are plenty of items priced at that already. Since Blizzard takes a $1 cut on every successful auction, the minimum is $1.25. Players who want to buy and sell using a Battle.net balance are, understandably, required to attach a Battle.net authenticator to their account. Other options include using a credit card or linking a PayPal account.
Equipment sales come with a $1 deduction (taken by Blizzard from the sale amount). Sales for anything else—like gems, crafting materials, and gold—take a 15% deduction instead of the flat $1, presumably to avoid loopholes of selling those commodities in large stacks. Gold must be sold in quantities of 100,000 or more.
Any money made on the auction house is subject to a 15% withdrawal fee if you want to put it anywhere besides the Battle.net balance (which can be used on the auction house, to pay for WoW subscription time and pets, or anything else directly linked to your Battle.net account).
How the IRS chooses to treat these transactions, either as business income, hobby income, or income subject to a floor (like their treatment of PayPal profits), is yet to be seen.
I'd be willing to bet that you don't have an unqualified right to the money still in Blizz's coffers (the rules to maintain an account are rather strict, and if you lose your account you lose your money), so it's not income until you cash it out.
