I"ve had one for the past five years, and have really liked it. Lots of power, and very fuel efficient. Have used it primarily for pulling a cultivator and baling.
Some of the more abused AC200"s will have transmission issues with third gear (and others) popping out of gear. Apparently, this was due mainly to impatient drivers forcing gears and grinding them in the process. No issues like this with mine; seemed to have been well cared for. Give it a good once over and drive (downhill if you can) before buying.
Pricewise, they tend to be a cheap source of power in our area. I picked up mine with 3000 original hours on it and a cab with heater/AC for just under 5K. Tires were good, and the paint/body were in excellent shape (had been stored inside). A JD 4020 in relatively poor condition was bringing 10 K at that time.