I created this tool that finds inefficiencies in market and utilizes that information to give you URLs for an item (like a college textbook) that you can buy cheaper and sell to a buy back service for a small profit. I charge 50% of the profit. You can rinse and repeat this as many times as you want.
Do you think this is neat? Check it out at http://flippiness.com/
Do you think this is neat? Check it out at http://flippiness.com/