The batteries I use are more expensive than I remember (may have gone up).
http://www.all-battery.com/index.asp...ROD&ProdID=202
Real world Drawing 300~400 watts it is a 8 ah pack
if you draw a constant 100 watts it is a 12 ah pack
If you do flat out (600 watt once hot) it is a 5 ah pack
Watt's up = The Shiznit
http://www.trextuning.com/wattsup.php
MAX output is 10 amps regardless of how heavy of a load you put on them, but that is probably a good thing (keeps the pack temp down)
I use there batteries in lots of stuff round the house, for the price they can't be beat. The AA's are better than the Energizer NiMh's in my experience.