Higher margins on custom-stuff... In college, I had a bunch of Bridgestone 400's. Decent fork and chainstay clearance for 700x32C tires (was originally 27 inch wheels). Some buddies wanted training CX bikes. Found a source for cheap cantilever bosses and got some dremels, wire brush, flux, solder and torches. I brazed a few, and learned some secrets on making strong bosses that don't crack off on the first squeeze of the brake levers. Some cheap spray cans of paint and good taping jobs and lots of clear coat, and we had great frames that looked totally awesome. I still have an unpainted fork with bosses soldered on.

What's wrong with taking a junker bike off Craigslist for $50, added $50 in parts and lots of TLC and maybe even brazing and some paint? Turn around, and sell the thing for $300. That's 66.7% margin on something that you might put a couple hours working on if you're prepared to do that kind of work and fast at doing it?