Do you americans have "Princess Auto" or is that just a Canadian chain?
Check this out:
http://www.princessauto.com/moreinfo.cfm?TAG=55236&SCAN=CANI'm considering dropping by and seeing if that switch fits Atari cones. Could be a good source for replacement switches for Missile Command, though I guess there wouldn't be a big demand for them otherwise (most people want them lit, right?)