Call this chap- he has a forklift company that specializes in electrics, but on the side he also buys and sells used industrial uninterruptable power supplies.
As such, he frequently has wonderfully "almost new" AGM deep cycle batteries to sell at substantially reduced prices. Usually in the 125A/H range.
I've purchased quite a few from him and to me they are about the best you can get, at 1/4 the original cost. He fully tests them for quality and capacity before he ships them, so you always get a battery in excellent condition...
Donald M Shumay