I think it depends on where you live. Where I live this is not uncommon. The local vet here charges $75 for the actual procedure, but when you add in the cost of the pre -procedure bloodwork, as well as the cost of boarding a bunny over night, taxes, etc . . It comes to about $150.
Also, it depends on how many vets in your area will spay a bunny. In my area there is only one "exotic" vet and one other hospital that doesn't speciallize in small animals, but will spay or neuter them. Due to this fact, they can pretty much control the prices as they see fit.
I used to work at the only vet in the city that had a fully stocked hospital. When onther vet clinics had animlas that needed surgery, they had to refer their clients to our hospital. It is still the only vet with 24 hour hospital care.
As a result of this, they controlled the prices. As I recall it cost somewhere in the $400 - $500 to get a dog fixed.