Way too much, that's how much. :] I'm a groomer at a veterinary hospital and once, when we were trying to figure out pricing, we called Petsmart & Petco to see what they charged for various kinds of dogs. They wanted to charge $80 to bathe a golden retriever. That's something our hospital would've charged $45 for.
Japanese chins don't really require much grooming. Just brushing and a little trimming where needed. Why don't you learn to do it yourself? Pick up a dog grooming book, check the Japanese chin breed club's website, get some basic tools, and go nuts! You'll save yourself a fortune.