I haven't been doing the C&V thing all that long personally (under 2 years), but I have amassed a large assortment of parts. The majority of parts came from bikes I purchased and then sold the frame/fork on CL to someone wanting to build a SS/FG or whatever themselves. Out of the last 34 complete bikes or frame/forks I have sold, 16 of those were sold as a Frame/fork (usually with BB and headset). I have also turned five of them into fixed gears that let me keep all of the shifty bits, wheels, BB, and some other parts.