If they're on the cheap, I always enjoy picking up old fast food wax/paper cups. I just found two old cups that are really fun looking.
First one is from Colonel Dixie Fast Foods, a small fast food chain started in Mobile, Alabama. I wasn't familiar with this fast food chain. Quick research shows that there's only one of these still in operation.
I'm sure many are familiar with Bonanza Steakhouse. This popular chain was started in 1963 by Dan Blocker who played Hoss Cartwright on the TV show Bonanza.