Before anything else, I want to make sure you know that you’ll still need your day job. People WILL spend real money on items and gold, but what they’re really buying is time. Assume you were going to pay someone an hourly wage to farm on your character for you, how much would you pay them. Take that number and cut it in half, and that’s what you can expect to make per hour of effort in Diablo 3. When it comes to the RMAH, there’s really only going to be 4 things people will spend money on (directly and indirectly).
The first and most likely to have a decent market is characters (Note: at the time of writing this, Blizzard has confirmed they would like this feature, but it is not finalized yet). Buying a level 60 character will save a player a lot of time, so it will be worth real money to them. If you have high quality gear for all levels, you may be able to level up characters much more quickly than a fresh player, which will be something to take advantage of when selling characters.
Gold is the next big thing that will sell for real money. Gold in Diablo 3 will always be needed by players, and will always be available while playing. The trick to effectively farming gold will be to stick to content that is a few levels lower than you such that you can plow through enemies more easily and collect the rewards. Gold is needed for repairs, upgrading your artisans and for buying items not listed for real money. There very well may come a time when even you would rather spend a buck or two on gold rather than farm it yourself. Also remember that since you can sell gold, it may be most profitable to sell other items for gold, and then gold for real money. This is important to keep in mind for the next two cash cows.
Crafting materials are acquired by salvaging magic items and are required to craft items at your Blacksmith. When you craft an item, it typically comes out with random stats. If someone is trying to roll the dice and get the perfect stat modifiers on their item, they might go through hundreds of materials. Odds are that people are not going to gamble their real money in this fashion. However, selling these salvaged materials for gold and then selling the gold for real money will result in profit for you. Again, the fastest way to stock up on items for salvaging will be to take on content a few levels lower than you such that you can breeze through it and collect more drops.
The final and most obvious thing to sell is Rare (and better) items. In most cases, you’ll want to sell these for gold. However, if an item is really desirable and well known (such as a Stone of Jordan in Diablo 2) then people will directly spend real money on it. You’ll probably have to do some research on the Legendary or Set items you find to determine if people want them badly enough to pay real money for them. As for magic items, it’s safe to assume that nobody will buy it and you should salvage it and sell the materials.
I know you think it’s going to be best to do your farming alone, b