Fluorescent Ballast/Fixture/Socket?

Hi, I just picked up a used four foot long, four slot, fluorescent ballast free on Craigslist. One of the sockets is damaged. I know it's a T12 ballast, what type of replacement socket would I need? Also, it's clear that it used to be hardwired, how would I go about wiring it to a cord that I could just plug into a standard 120v wall socket? By the way, there are actually 2 ballasts inside, each one controls 2 lights, would I need two cords or could I wire them both up to one? Thanks.