I get my eggs right now, until mine start laying, from a guy in Enumclaw who has basically modified every second hand thing he can find to accommodate his animals (think railcar, lean-to's, etc). He has a dog house that he uses - up on 4x4 legs with wire mesh surrounding it - and a little ladder going down to the grass. It is a wood dog house - 4 feet x 4 feet and he just popped out a hole and covered it with mesh for ventilation at the top, and put two nesting boxes in there. Plus one roost. There appear to be 4 hens using it. I am the geek that goes and walks around his pasture with him, oogling his inventions...
I have done almost my entire shed conversion out of "found" objects and the only thing I have had to buy was mesh and paint. Lot's of mesh. And not cheap either, but so neccesary.
Craiglist, craigslist, Craigslist....Let me sing the praises of Craigslist.