The battery chargers look like a good deal, but other than saying for Mobile Home batteries he doesn't give any specs for them. The deal may not be as good as he says.
Here's the best comparison i found for offboard battery chargers:
various chargers
the batteries he mentions appear to be dry cell automotive batteries.
Link for Stinger SPV70 ($260 USD is the high end price range for them new)
I'm afraid i can't give any more info on the other material. But if you find he's charging too much for something like the charger or batteries, then the deal for any of it may not be so good. (also be sure the batts hold a charge.)
[EDIT:] by the way, you might beat me in the EV Building Race, it looks like my house may be heading toward some money problems. But that doesn't mean I'm giving up!