BlueLudeSI94 is talking about the 4th gen S model Prelude, so that doesn't really apply to you since you're looking into a 5th gen. a 5th gen Type S does exist though, but outside of the US of course.
since you're in SoCal, I'd probably look into
SCP - SoCalPrelude.com :: Index to look for some used Preludes. other than that, the normal places like auto trader would be a good start.
as far as common problems there aren't very many as the Prelude is a very well built car. you're going to want to get a 5 speed for sure, as the automatics are severely problematic. besides, the Prelude should be driven with a 5 speed because it's a great sports coupe. other than that, just make sure the transmission shifts well, 2nd and 5th gear grinds do happen.
good luck, and welcome to PO!