This is kinda cool, and I'm surprised I never heard of it before. Habitat for Humanity (the charitable home builders) have a chain of discount retail stores called Habitat ReStores. It's basically a handyman's Goodwill! Their website says:
Materials sold by Habitat ReStores are usually donated from building supply stores, contractors, demolition crews or from individuals who wish to show their support for Habitat. In addition to raising funds, ReStores help the environment by rechanneling good, usable materials into use.
I stopped by one in Gurnee, Illinois yesterday, and that's definitely what I saw. Row upon row of reclaimed doors, lighting fixtures, cabinets and hardware, plus partial cans of paint, partial rolls of wallpaper, and the like. The place was packed, and some of the prices were excellent (as in $5 apiece for some cheap reclaimed cabinets that were on clearance)! I'm thinking I may need to check it out when I'm ready to build the back-bar in my slowly progressing rec-room. I just wish I'd known about it before I bought all of those doors!
PS: This may be a good place to go with those out of date cabinets you've got from your kitchen remodel. Get em out of your face, and do some good in the process (procedes go to fund Habitat houses).