The average cost of a declaw can range from $100 to $500. Some vets will no longer perform this surgery because they consider it to be inhumane. The cost will differ depending on the method used. The most expensive and humane way to do it is to use lasers. http://www.vetinfo.com/typical-cost-to-declaw-cat.html#b
It depends on the vet that is performing the action. Some are as little as $60, while other can be up to $300. It is recommended to only declaw the front paws; otherwise, with both all paws declawed, the cat will have no way to defend itself.