It depends on the vet... mine likes to charge an arm and a leg... but I've heard of a few vets in the US with some pretty good pricing. You'd have to call around, ask them of their knowledge on rats, if they have ever did rat surgeries and their prices.
Oh dear... have you called around already? If you are looking online, google your town/city and add exotic vet or you could also search rabbit vets, chinchilla vets. Chances are if a vet treats ferrets, chinchillas and rabbits, they will know rats too.
Yes, you really want a vet that is experienced at doing surgery on rats ... and rat neuters are different then cat and dog neuters.
Please see the sticky on things to discuss before surgery
and Jorats vet is willing to consult with other vets re. rats so that is an option if you find a good vet without a lot of experience with rats.
As for prices, that varies from place to place and vet to vet.
In this city, one vet charges around $45 for a rat neuter while another charges over $200.