List of suppliers
This is a list of sources for 24 volt parts and pieces. These companies listed below don't really specialize in 24 volt stuff but are good sources for military and industrial surplus, like relays, motors, solenoids, light bulbs, etc. I especially recommend Fair Radio Sales and Surplus Center but I've done business with all of them. All have catalogs, too, but the one from Surplus Sales of Nebraska will cost you $5.
-Bob Ragain Littleton, CO
If you know of other sources, please let me know.