Okay, first you have to ignore the clerks. They are normally ... special people. What you need is a momentary switch. I can't imagine them having nothing usable. The switch you need has two leads. One in, one out, and it'll be labelled "momentary" (I think the actual terminology is SPST). They should have dozens (every one I've been to does ... where are you?). If that doesn't work, try an auto parts store, they normally have toggle switches and push button switches for the crazy stereo/CB crowd.
If anything else, go here:
http://www.mpja.com/list.asp?dept=63
They are designed for computer use.
This one would look nifty, if mounted right:
http://www.mpja.com/product.asp?product=5020+SW