It takes an iron man to play with a toy iron horse.
I can't find any bill operated timers...not sure if they exist as a standalone product or not. You may have to use a bill validator and use it to trigger an electronic timer...?
http://www.thomasnet.com/products/timers-coin-operated-machine-85620805-1.html
Here's a list of coin operated timer manufacturers. I'd bet some of them make dollar bill versions too.
I'm working on a public model RR display. I'm looking for an adjustable timer that is activated by the insertion of a $1 dollar bill, which turns on 110-volt power to a standard power pack for X minutes.
I may not know what to call the item. I know they exist.
Anybody know where to find such? Will appreciate any clues. I have contacted a major electrical supply company and have done a Google search.