I just bought this PSU, is it good enough for my build?

Besides the fact that it's used which I don't like, yes, it's fine.

How much of a risk do i get when buying a used PSU? I figured its a trusted seller, but honestly i searched and saw there was 50sec left so i just put the minimum bid for the heck of it. Is antec a good brand though or is it like shity Ultra I'm upgrading from a Ultra X2 750, and that only ran 1 GTX 460 =(.

Antec is a good brand and if it's a True Power NEW, then it's a very good unit, but the risk of buying a used PSU (or anything used, really) is that you have no idea how long it was used and how hard it was pushed, unless the listing says, which that one doesn't. If it was only used for a month or two and was never really pushed very hard, it's probably OK, but if it's a year old and was pushed to its limits, that wouldn't be very good, obviously.