Be careful purchasing anything on Craigslist as it’s a free for all there. I think Apple sells refub’d gear with limited warranties - check that first. If not - check out e-bay and look for a store that offers limited warranties.
Actually I found a company that sells refurb’d macs. I found one there with an OS X, 512 ram, 80 gb hard drive for about 250. Is that a deal too good to be true?
It had a limited warranty also.