craiglist

I built my rig during my senior year in high school and now find it just collecting dust once I went to college, I just don't have the time to game anymore. I was just wondering what you guys think this PC could sell for now. Here's the part list, some of the parts didn't have prices attached...

I saw an ad on craigslist of a guy selling his 1070 8gb cards for 100$ and he said they were well ventilated and never overclocked only used for 3 months in short bursts should i buy the card?

if my pc just requires <450w. whats the different when I use 500w psu and 750w psu. is the 750w psu will increase my electric bill even my pc just requires <450w?