Agreed. Find a mac addict on craigslist who bought one right before the new ones came out. Spend 50 bucks at crucial to max out the memory to 4GB. Mmmm. Tasty memory.
Not a bad idea at all, finding one that is affordable is critical. Also, I don't even own a mac other than my powermac G4 and I still check (macrumors is it?) that one site that has a guesstimate on when new models are due to come out. That way if I buy a new one, I don't get screwed.