I just got a Griffin case for $20
I had a couple of cases for my iPhone 3G and the Griffin Reveal Case, being one of the cheaper ones I’ve come to own, is also one of the most practical.
It’s clear on the back, black around the borders and is pretty spiffy looking.
For $20 bucks you can’t go wrong. If you are looking for a decent case that won’t break your wallet, check out the Griffin Reveal Case