i think bostontrevor has been giving out some great advice here, kurrenkarm. I'd add that maybe explaining your experience with bike shops in the past (even if its the same one!) and the resultant fears you've developed may kinda put the ball in the bike shop person's court-- s/he might take it as a challenge to give you good service, a fair deal ($45 fitting sounds like Lance BS to me), and prompt turnaround (or, fair warning if it'll take a while) on any special orders.

i've always found it easiest on me and the shopguy if i'm up front in a polite but zero-tolerance-for-BS way.

hth,
-rob