I have no idea about value of carts and resale. I buy an electric cart for about $2000 and I run them into the ground. The problem I for see with circa 2002 club cars is they they never stop running. I suspect I will sell one when I can get an EZGO RXV AC drive for less than $2500 to have some fun with.
I have no idea about gas carts, never had one, never worked on one. I always fixed my ride on mower so I suspect I could be trained. I understand why people own them.
Deep cycle batteries on the other hand I know something about, not a lot but enough to help. Everything about an electric cart is about usage, YOU the buyer need to define the usage. As an example if you buy a Club Car Precedent with 4-12v batteries and drive it 40 miles per day, the batteries may last 18 months. Use the same cart and only go 10 miles a day and they may last five years.
You will need some training for an electric cart as far as battery maintenance. It should take the average person about an hour to become an expert like me
How one budgets for batteries really depends on how well they maintain their pack and how deeply the pack is discharged daily as I mentioned above. I budget $250/year per pack.
My budget is a guess as I have only owned two packs
from the beginning and they are both still operational. One of the packs will be
four years old in Feb 2014 and still going strong. Not as strong as when young, but who is? When they were just over two years old I drove them 63 miles and still 47.6 volts in pack. It is less than 12 miles from Spanish Springs to Brownwood, I leave the math to you....
That pack is 8-6v batteries and cost $770.
You will read alot of silly information on this site about electric carts and range, so you have to dig a bit to get some facts. Good luck!