I made a working AH bot with two functions so far. The bot searches repeatedly for whatever you want and, if it finds it for the price you specify, buys it for you. You can make a list of multiple items/prices and it will search for all of them. I recently got it to be able to compare the prices of items and buy the item with the cheapest buyout if it is 20% cheaper than the next cheapest item with a buyout. Then you can put the item right back on the auction house (still as the cheapest item with a buyout) and ensure profit.
I saw another post on this forum asking if this existed, so I figured I would mention something and see if there was enough interest for me to continue development.