As I mentioned to Bigiron in another thread, I found an inexpensive source for copies of plans:
UPS Stores, I guess mostly in large cities, or places where there's a lot of construction work going on, have large 100% copiers. The paper is not eternal archive quality, but quite good.
The copies I got at my nearest UPS Store were the most accurate first-pull copies I've seen in years. On a light table or against a plate glass window/door, the lines superimpose - dependably.
For how much? Around here, $2 plus sales tax per. (Pretty much single width, length irrelevant!)
Might be interesting to see how widespread these UPS Stores are around the country...