Sure, it's really cool to recycle, but as an example, I'd insist upon pre-hanging a set of old doors into jambs made of recycled lumber in a shop, then installing the jambs/doors on site. That's really labor intensive and it costs lots.

Hang around the Habitat Restores - there are some in your area. You could also ask at any architectural salvage yards you may be shopping at. We were DIY and used a lot of recycled objects - including an old lab sink in our kitchen that we had found at a plumbing supply store in Mpls.