If you live in northern New Jersey, you are probably paying top dollar for services. I have heard routine dentals are about $400-500 in the NYC area.
With that in mind, I don't think that is outrageous for what your vet has included in the estimate. It's not a routine dental since Gracie needs extractions.
The cost of dentals usually surprises people the first time they go through it. It's one of the expenses a lot of people don't think about when they calculate the cost of owning a Yorkie. Yes, some need it done every year.
It certainly wouldn't hurt to get a few estimates, though.