if the compressor went than flushing and replacing the receiver drier is the right call. I have only seen one failed compressor on a Honda in all my time as a Acura/Honda tech. I would say the shop isn't neccessarily trying to rip you off as it is generally protocol to replace the receiver drier when the compressor crap, but I would say 40 bucks for a compressor at the junkyard plus maybe 100 bucks to have a local shop recover/vac/recharge the system is a hell of alot better than 850!!!

edit: Also I would def. check the tension on the rest of the accessory belts. Most techs don't bother actually checking the proper tension when installing new belts but go with the "yup that's tight enough" method.