We charge $60 for the microchip as well, but offer dual registration to our hospital, if the owner can't be found, the animal is boarded at our hospital until pickup is possible.
Just want to clarify something, spays on larger dogs are more expensive because they take longer. The anatomy is bigger, suture is larger (and more expensive), and there is a lot more fat to deal with around the uterine horns and uterus. This is also why spaying a dog in heat is more expensive, lots more blood flow = more vessels to tie off and everything is engorged and difficult to work with.