I'm looking for a reliable online shop for fixed-gear/single-speed parts. I have a frame and fork and am wanting to buy new, quality parts to complete my first build. Any suggestions?

Specifically, I'm looking for a fixed/free wheel-set, cranks and cogs. I've tried my local bike shop for these parts, but unfortunately they were not very helpful after mentioning single-speed (they were cool about it, just uninformed).