This is what I use for bird photography along with Powerex 2700 mAH batteries. I can get several hundred shots no problem but I am using only using fill flash. I use a 580 EXII usually in ETTL mode at around -2 1/3 stops.

http://www.outdoorphotogear.com/stor...tery-pack.html

I know you said this isn't what you want but it is a fraction of the price of the Quantam packs and it works quite well with fast recycle times too, of course dependent on the flash settings. I looked at the Quantum products and they are very nice but they are very pricey. This Phottix unit is identical to the Canon battery pack but much less expensive.