"low end" was probably a little extreme from JN, but we discussed the NEX lineup early EpicLegends. It's far from the best, but could be a lot worse. Used PSUs are not very desirable to begin with, but 'top of the line' (at least PSUs that were top of the line when new) do hold some resale value.
I agree that you should take anything >$500. I'd actually suggest anything >$400, or part it out. Between the CPU+Mobo+RAM & GPU. you could probably recoup at least $300-$350 right there, with storage, a case & a decent-ish PSU to reuse yourself.