Great points and best management practices, and you guys have some very nice layouts from what I've seen on the forum and in Dave's case, via magazine and video.
I was able to recycle most of the dimensional lumber, wire, screws and bolts and switches from my last layout. I could not salvage the plywood nor most of the Gargraves track (it had been ballasted). This greatly help offset the cost of my present layout, notably the copper wire, which may have been a mile or more in total length.