I have an Apple Extended Keyboard which I picked up from a junk heap a little while ago. It's yellowed and probably a tad gunky inside. I found what seems like a good description how to clean it here, http://lowendmac.com/thomas/06/1013.html, but I am wondering what I could/should use to de-yellow the outside plastic. I've heard of retrobright and I'm sure it works, but is there something a little easier to obtain that I could use instead?