If you're trying to build what coin collectors call a "type collection," I would at least have these three 35mm SLRs: Canon AE-1 (a very successful mass-market auto-exposure 35mm), Pentax Spotmatic (any model), Nikon F (it's a Nikon F, it's a first on so many levels; google it). If you want to include auto focus, I'm not sure what model to suggest there, maybe one of the first Minolta Maxxum cameras (first successful mass-market AF 35mm)? Also these three 35mm rangefinders: Yashica Electro 35 GSN (it's pretty), Argus C3 (many people learned on this camera), and if you can budget it, a Leica M3 (first modern Leica).
There are other 35mm cameras that are worth including. I don't know enough about medium or large format to have a real opinion, but I would have a Speed Graphic and a twin-lens reflex. "Amateur" cameras are so numerous... maybe a 620 folder, a box brownie, a 110 camera? And a Polaroid Colorpack - there are so many models, pick one.
This would be a wide variety covering a large range of 20th century cameras. Many of these can be had for small amounts of money, especially if they don't work anymore.
Last edited by rthomas; 08-25-2011 at 10:39 AM. Click to view previous post history.
Reason: Kept thinking of things to add...