not great, a GTX 650 is very entry level, it'll struggle to play the latest games on high settings, if you don't mind medium ish settings then it's fine. If you want a decent gaming rig you'll not want to go below a Radeon HD 7790/R7 260x, or a GTX 650Ti Boost/GTX 660
the one from ebay is probably your best bet, it comes with a 1 year warranty after all so may not be as risky as you think