Psychology is a funny thing - as pointed out, we dropped the equivalent of $1 game as kids and never thought twice. And granted EM's don't have the deep ruleset of modern pins, but a good EM can challenge your skills as just as much.
Appreciating them for what they are and knowing what goes into maintaining them (owning one myself), I think the $1 is justified, but my concern stepping up to play an unfamiliar EM would be - does it really work right? Even if it looks in good shape, EM's can be finicky in their old age and I might hesitate to drop a buck into an unknown machine.
But 50c - sure.