I've become somewhat fascinated with the auction house recently. The majority of sellers do not appear to understand how to properly price items, so it's hard to find things that are worth buying. However, the general lack of decent pricing seems to make it relatively easy to sell. I've sold about 7 items so far, for a total of about 40k. I may be undervaluing them a bit, but they sell quick and that return is a lot more than I would have gotten for the goods from the merchants. In addition, it's totally pointless to craft gems of Radiant quality or below. It costs 3500 gold to craft a Radiant quality gem, but you can buy them on the auction house for between 500 and 1000 gold, depending on whims of the market at any particular moment. Every tier below that is similarly cheaper to buy at auction than to craft yourself.