I purchased a replacement battery for my PowerBook G4 12” Aluminum (I think you meant PowerBook not MacBook, right @ttunguz?) from FastMac as I had heard great things about their batteries. Ultimately I’m going to have to say that I’ve been disappointed with it for the following reasons:
+ the material they used isn’t the same as the PB aluminum—it feels more like plastic to me
+ the little foot in the corner fell off pretty quickly
+ the battery didn’t match up perfectly with the body of the PB so there is a slight lip from the battery on the right-hand side of my PB
That being said the battery works and holds a charge, which the original battery no longer seemed to be able to do.
If I could go back and do it again, I think I would just purchase it from Apple. I went with FastMac because I was trying to save a few bucks, but its worth the extra $30—$40 to have it match perfectly, imo.