The compressor can go out for a lot of reasons. Low oil in system, leaks, dirt or moisture ... the list goes on. The price is high because for one, you are at the dealer. Also, if the compressor grenaded it has put meatl parts inside the whole a/c system. they need to replace the compressor, the accumilator ( reciver/ dryer) oriface tube. they need to flush the system to clean any debris out of it. then they will evacuate it after installing the new parts for an hour or so to remove all of the moisture. They will let it sit under vaccum for another 1/2 hour or so to see that in holds a vac. and has no leaks. Then they will recharge it with freon( not cheap) and test it agian for not only cold but for leaks . They may have found another problem that caused the compressor to go out and have included that repair in the cost also. Call around some of the local aftermarket shops that do a/c and see if you can work a better deal.