I buy parts collections and cars whenever I can and sell until I have my investment back then I store the rest, then when I get to my project I pick the parts I need and start selling ones I probably won't ever use, until I have all the pieces I need to fund my current project. Doing this with my current project a 1932 3 window with a blown v12, and so far I've not spend any money out of pocket.. and I'm probably over 80% there with the money I need. Example.. I bought a firetruck for $2,500 because I wanted the engine. I sold the fire fighting equipment for $2,500, kept some of the cooler pieces (dash and such), made a frametable out of the frame, a welding table out of the truck bed divider and traded the body for another V12. End results.. my original investment came back to me, I have two complete v12's a set of cool lights and miscellaneous parts, a welding and a frame table, only invested a couple of days of time to get it all parted out.