If it starts, runs and stops, makes no nasty noise and has no water in the oil, you're good to go. The big ticket items are the motor and transmission. If the coolant is straight water, there's a good chance it has blown a head gasket and the owner just topped it up with water. Look for water in the oil (milky beige sludge under the filler cap). Check the transmission works in all the gears, hot and cold. Expect parts to be worn and maybe need replacement but they can be fixed later. If you can do the work yourself, fluid changes are not that expensive.