I started researching 12V golf cart batteries and ran across the 150Ah Trojan T 1275:
Most of the people on the golf cart forums prefer the Trojan batteries over any other brand, at least from my limited scanning.
There is a Continental Battery location right down the road from my office so I stopped by this morning to check pricing and availability of the T 1275. They had them but for less money they also had the same battery in their Continental brand.
I was blown away when they said the price was $120 with a core and has a 1 year warranty. I'm pretty sure my battery search is over unless someone strongly objects or has had a really bad experience with these batteries. It looks like I may only be able to fit 2 of these where I want to put them.