wa1, yes I love this PSU. I took a chance on it, considering everyone said to stay away from OCZ, I couldn't beat the newegg price when I bought it. I still will never go with OCZ Ram though. They use to be really quality, just has gone downhill since.
I watch the used section of HardOCP rather frequently. A used 512MB 4870 would normally go for about $80 shipped. If your doing this local, $70-80 would be "normal". If you can get it for $50 thats great, but don't be surprised/insulted if he says no.
My brother inlaws friend, and he's getting a 6870 for x-mas. If he don't want 50 bucks for it, then he can try and sell it to someone else. I'm not willing to pay more than 55 bucks, but I do get what your saying