I'm selling a EVGA GTX 650 Ti SSC on eBay right now. You can certainly buy there or PM me here! If you PM me it's easier to negotiate price and shipping. Right now it's free USPS shipping in the US, but for other US carriers or international, you'll have to pay.
It's in my rig now, but I've only had it a few weeks! I don't need all the power, so I'm looking to go down to a Radeon 7750.