Mine came from the factory with A/C. Yes, it is expensive. If it works out, I'll be happy. Since the car is like 27 years old, the rest of the components needed replacing. So if you figure out the cost of a new or rebuilt compressor, and if rebuilt how long will it last. New condensor, new evaporator etc. Then it is about half that. Some of the hoses are like $250 or $350 each. Now if the performance claims of less HP needed to run the compressor are accurate (3-5 hp vs 12-15 hp), then it might be worth it to some extent. I wouldn't spend that kind of money, if mine was a rust bucket though.
Tom