Well there is the pipe dream of building a lower-cost bike, but for me at least there's also an allure of having a unique bike at the end, that has a story and special me-ness that a store-bought stock bike wouldn't. Kinda vain I know, in the end it's really about the image my bike helps me to project, or at least see myself in.

Plus I simply derive entertainment from screwing bike parts on and off of bikes. Frankly, I'd rather buy a bikesdirect.com bike than an equivalent LBS bike or even craigslist bike, just because I would get to assemble it. If REI or Surly offered a CrossCheck build kit in a box (nothing assembled except for wheels already built), I'd find that attractive. Or in general if there was a brand or website that offered a la carte bikes (pick all your own components) at OEM + 20% prices, I'd be shopping there in a heartbeat!