How much would it cost to fix the heat in a 01 eclipse? on 2001 Mitsubishi Eclipse

Looking to buy one, but the heat in it is bad, and I need to know how much it would be to fix ir

Asked by for the 2001 Mitsubishi Eclipse
Would need to be diagnosed to determine the cause before an estimate for repair could be given.--Heater core blockage , thermostat stuck open , blend door failure etc.?