My online shopping has primarily been done at badgergraphic.com (Jeff is awesome), mpex.com (Jim Andraki is also great), and keh.com. I built my 645 kit from mpex.com and keh.com for cheap, and everything was in perfect condition. I've purchased 4 4x5 lenses from badgergraphic, with great service from Jeff each time.
I've also dealt with B&H a couple of times (ok experience, really expensive shipping), and Freestyle (I bought so much stuff, they threw in some freebies).
I've not had a bad experience with any of them. All recommended.
Oh, I have bought stuff from Calumet, but only from their store in S.F....never over the net.