I recently shopped for a LiFe battery replacement for my P80SE, and they were extremely hard to come about. I decided to buy a 7.4 LiPo that Dreamworks carries. It is a ROAR certified package by Exceed R/C (for R/C cars). It comes on a very hard case, which in my opinion is far more robust than the packages we are used to.

I like it so far. LiPo is goo stuff for kero starts, but they do need careful handling.

David