The Humane Society of silicon valley charges $125 for euthanizations and $25 for body removal costs. 15 years ago they did for free. This is similar to what other nonprofits now charge. My local vet charges $110 for the euthanization and $105 for the cremation -a mandatory cost, plus charges for physical examination.
In the Midwest, this is a pretty steep charge - most veterinarians would likely charge less than $50 for a simple euthanasia.