Is $530 too much to neuter a 15-pound dog?

We live in Maryland and took our 7-month, 15-pound Cavalier King Charles to get neutered this morning. The price, including all the medication and collar and all that, was $530. This seems really high and they didn't tell us the price until we were there to drop him off. After dropping him off I called other vets in the area and the quotes I was given were between $200 and $350. I know clinics are way cheaper. I should have gone to one of those. I have been ripped off, no? I'm going to pick up my dog this evening and pay the bill, but is there anything you would recommend I do when I go there? I know they won't likely lower it, but how would you guys handle this situation?