Rev and joystick or switch

[David Glasgow]

I want to use a switch (lever style accessibility gadget) or a very  
simple joystick to enable users to respond to images by pushing away  
or pulling towards themselves.  It needs to work on both Mac & PC.   
Fewer buttons the better, and no flash rumbling or stuff like that.

Any suggestions for simple and preferably cheap hardware that folks  
have used with Rev?

best

David Glasgow