I just visited Van der Haag's Truck Sales/Parts/Service south of Council Bluffs, Iowa (near Omaha, NE). They have about a dozen or so "junked" buses that have good bodies and may be usable for parts & body metal. Manufacturers: Blue Bird, Carpenter, Superior, Thomas, Ward/AmTran, Wayne. They also had two IH/Carpenter conventionals, a 1985 and 1991, in the regular (roadworthy) used-vehicle section. Three locations in Iowa: Spencer, Des Moines, Council Bluffs, and in Sioux Falls, SD. No RV parts or salvage, though.
. Not a huge selection, but worth checking out.