I've been to the Alexandria Spokes. Good shop. Seems to have good people who will probably fit you properly. Don't get a bike from Performance.

While you may save some $ buying second hand, it's not the best if you don't know much about bikes yet and what you need, or what parts of the bike to inspect (and what to look for). Plus, some shops will give you free services, swap components, and developing a relationship with them can save you more cash in the long run.