I would NOT go back to a shop that charges $250 for $40 worth of REFRIGERANT (coolant is what you put in your radiator.)

I just bought 30 pounds of R12 for $425. That is what that shop pays for it now. DON'T patronize such crooks and don't convert. R134 is going up in price drastically this year so it is almost as much as R12.

Good luck,