The EF 50/1.8 is dirt-cheap and pretty good. For a bit more money, however, my experience is that the 50/2.5 "compact-macro" (it only goes to 1:2) is a significantly better lens for general use. It's one of the oldest EF lenses, so there should be a decent used population.

The autofocus isn't great in my experience, but it makes a terrific noise, and some people are happy with it. I don't know if there's sample variation, or if I use it in unusually difficult focussing circumstances, or what.