http://www.chiefdelphi.com/forums/sh...threadid=18299
I described our dongle there and included the Digikey part numbers and page numbers for digikey buttons. Check the catalogue and get the style you want, though. The full thing is about $15, but what I did is I just bought the button itself (no switch mechanism - that's another $6 or so) and just attached a spare computer switch I had lying around.
Just beware: Digikey has a minimum order price of $25 - anything below that, you have to pay a $10 (might be $5) surcharge. You're better off finding out $10 worth of electrical components your team wants. Either way you pay $25.