The only other color I've seen for that style reject button is orange.
There's a door on eBay right now that looks like it has orange buttons (should verify with seller):
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3245706977&category=13718I like the orange ones better than red, they seem to have a brighter, more even glow than the red ones. Sorry, I don't know where you can buy just the orange buttons, though. If you really want orange ones, you might need to eBay a whole door, do the switch-a-roo, and relist the door... Just an idea.