The cats rates are $50 and dogs were $80. It's quicker to have a bullet in the head than paying for a vet to humanely put the animal down.
I've done it with our pet dog, it was hard but had to be done. She was suffering badly. Our vet would have done the same thing when we were given the choice, either pony up the $50 for the shot OR pay 50 cents for a bullet and $25 for his call.
I remember during vet class, the quickest way is to fill up a huge stringe of air (we were doing horses), pop it in their jagular vein, and down they go. It was very quick.