Hmm, I think you guys overlooked something. Why illuminate under the keys? Why not get LCD screens on each individual key?
The Optimus
Granted this is going for 60 times what you want to pay, but you know...just save up your money a little.
Here are some other solutions to your "Unable to see at night" problems:
1) Can't see the keys at night, can't see the keys during the day...
Das Keyboard
(This keyboard is 4x what you want to pay so it's not the best solution)
2) See the keyboard the
Old Fashioned Way