Just my $0.02 of course, but I like used boards. As long as you check them out carefully then it's pretty hard to get a dud. Lots of money can be saved, and you won't care so much if you take it over rocks, etc.
One thing I've seen is some sellers will get them base ground and sharpened prior to selling. While this may be because they had lots of base damage and needed a grind, it also means the board is likely ready to go without having to invest money into. I recently bought a Burton Custom for $220, including bindings which I'll sell for about $70, but the edges were dull and it hadn't been waxed in ages. Still a good deal but it needed work right off the bat.
As for board types, if you're looking to do advanced freeriding (steeps, trees, etc.) I would suggest camber underfoot, with lifted tips. Something with an RCR profile, or whatever they call it. A lot of the Jones boards have this profile, Priors, and I'm sure there are lots of others out there.