I agree with above recs (except for ones I haven't shopped). ebikestop.com in Colorado has A LOT of parts that are hard to find elsewhere. For example I got a Miche (Italian) 9 speed cassette for Shimano/SRAM that easily disassembled to individual cogs, to make an 8-speed cassette (with 9-speed spacing) for an old 7-speed alu frame and hub. They also have loads of bartape brands and color /pattern choices.

Don't hesitate to google what you're looking for and price-shop. For example, I was just looking for some Schwalbe Dureme touring tires, and cyclocamping.com popped up. Their price $60 (each) was way less than wiggle ($77), which shocked me because wiggle (and other UK/Irish) stores normally consistently beat American stores significantly on Euro-product pricing. (I hope I'm not getting blems, will have to find out.)

For apparel, worldcyclingproductions.com in MN normally charges MSRP, but they have frequent 10-20% off sales. Just get on their email list for coupon codes. They sell quality products.

brandscycle.com in NY has gotten my business a few times, for sale items. One time I ordered some Sidi shoes, last year's model, their website did not show out of stock, but they were. So they sent me the new-year model for the same price. Very nice people to talk to.

I got a bike-build online from bikesale.com (Bothell WA). They totally underpriced CC. They gave me very knowledgeable advisement (everything they said worked out to be true), and even went so far as to contact Speedplay about making a set of long-spindle Light Action pedals, which Speedplay said, "Sure we can do that." John and Kyle(?) are really friendly. And the build was perfect out of the box. I didn't specify cables, they installed Gore Ride-Ons. I asked for tire rec, they said GP4000s were hard to beat (and they charged me $90 for the set). I asked if there was a carbon bar that could accept clip-on aeros, they recommended an Oval Concepts model. They had a good answer for every inquiry I made.

jensonUSA works well for me in Kansas, because I've noticed 2 day shipping with cheapest regular ground UPS orders several times, and then noticed the stuff wasn't sent from Cal, but from MN (QBP warehouse, methinks).

Most of these stores started as LBSs, so they know their stuff and you can phone-talk with knowledgeable cyclists and mechanics.