I only buy what is useable or can be repaired. I take some chances sometimes on low priced items and hope they are those two conditions. I'm not a stickler for perfect quality, and use what I have be it scratched or dented, as long as I can get good images out of it. Whatever I can fix I try too.
Cameras that I don't use, or cameras that are unrepairable are let out to my students to use. Some borrow them for the entire seasonal schedule and do get beat up or lost. The broken cameras are used for showing the internal mechanics and functions of the camera and get passed around for students to explore and prod to help them understand things such as the path of light, shutters and speeds, focusing screens, lens apertures, film take up etc.