I'm currently shopping for one too. We had an older one we picked up from a guy that refurbished them years ago. The batteries eventually got tired. "Upgraded" to a cheap sxs and after 1000 miles putzing around the ranch, it's blowing smoke and needs a motor rebuild. Want to go back to batteries because lower maintenance and it's easier for Mom to just plug it in once in a while than deal with gas cans. Also much quieter.
Things I'm learning...
Stick to the big 3 brands, parts and upgrades are readily available for Club Car, EZ-GO and Yamaha, even 20+ year old carts.
36 vs 48 volt. Generally 48 volt is better, but a 36v with six 6 volt batteries may be a better choice than a 48v with four 12v batteries. Simply more mass of battery will give you more runtime and battery life span of 6v should be better too.
Carts older than early 90's tended to use resistor coil speed controls. They are really inefficient as they dump power to resistors for anything less than full throttle. So even if you're just putting along, you're still using a lot of battery power. They can also generate a lot of heat which can be a fire hazard in the weeds.
Seems like $3500-4000 I'm seeing carts in good condition that claim to have fairly fresh batteries. Just want to find one that isn't a road trip to go get.