The cost depends on the size, type, age, condition, and location of the pool. It depends on who will care for it. Would you hire a service or maintain the pool yourself?
I sold a few homes with pools and the cost varied. The indoor pool owner did not use a service. He bought the chemicals in pill forms and that was the extent of his effort.
A service company can open the pool in the spring and close it in the fall for you. Your cost would be only the chemicals, as long as you do not mind the work. I would call Dixon Pool Service and others maybe to check prices.