go for the dual 6V golf cart batteries (in a well vented enclosure, of course.) Costco sells 220ah@ 20hr 6volts for $75.99 a piece. They are manufactured by Johnson Controls and are 63lbs. Additionally, they are rated at 100min@75amps and 425min@25amps respectively.
No, they're not spiral or gel cell or AGM, but those are the best numbers you're going to get for the money. By a LONG shot. With an 80 or 125W panel and an efficient controller/converter setup, I think you could pretty much live indefinitely in the boondocks with this rig.