The most important thing is buying a bike that is the right size. If you're not a very serious cyclist, then components arent as important, but no matter what level a rider you are, fit is always important. Upgrades can be made to any bike, and cool parts can be transferred to your next bike if you want. Id say to stick with Ebay (bang for buck) and keep your eyes peeled for a 52cm framed bike..

my $000.02,

~Steve