you can get them for $65-70 each, they look just like a lawn and garden battery except they don't have acid in them. I would buy the Power sonic brand, some of the other brands are "unknown" and you don't know what you'll get haha
I would look into group u1 deep cycle SLA batteries. They are used in the large power chairs for old people. And are rated for 35Ah and 12 volt, and won't leak acid or spill. They weigh 20-25 pounds each where as a regular group 24 wigs 45-50 pounds each and can't be inverted or they will...
I just finished building this, and thought I would post some pictures. It is painted Kawasaki lime green and has a Predator 6.5hp engine on it. It has 14/72 gearing and does a gps verified 31-32mph, and does roll on wheelies very nicely. :cornut: