So I've been meaning to upgrade to a better card but seeing as I have a gtx 960, I didn't wanna buy something like a 970 at full price since its about 50% better at around 300-350 bucks, especially considering that the gtx 1070 is coming out in june. So I went on some forums and found a guy near me who has a GTX 970 (reference card, modded white and black color, never overclocked (so he claims)) for 200 bucks USD. I'm very tempted to buy it, but I wanna know if this is a good deal. The warranty on it is obviously very likely to be voided since he modded it, so if it craps out, I'd kinda SOL, and I've also never bought any used parts before. Apparently its usually safe if you know what you're doing, but should I take this offer?