Yes, California is pretty bad when it comes to prices. I had people calling our hospital all the time to place 1800petmed prescriptions.
The way it worked at our hospital, is when the doctor prescribed something for an animal, the person could opt to use the 1800petmeds if they wanted. When they opted for that route, we faxed in the information to 1800petmeds for the owner. So, to answer your question on how it works: Yes, it does require a vet's note or a copy of the prescribed medication faxed from a vet's office.