The best radeon GPU's in that price range are the 5750 and the 5770, depending on which deals you can find for them. I see quite a few new 5750's for 124.99 on ebay and quite a few 5750's on newegg.com for around $115-125. My recommendation for you is the SAPPHIRE Vapor-X 100284VXL Radeon HD 5750 1GB for 124.99 on newegg. It's cheap, has a great cooler, and has some pretty solid reviews. It's generally better to buy from newegg since their return policy is much better. You also get the 2-year manufacturer's warranty; something ebay sellers generally don't provide.