Like boxtops, I think insurance is an absolute must. It's a tricky one. If I were a vet I'd really struggle with turning a sick animal away.
Last time I had to take one of our cats for some minor treatment, it cost me £60, but when I thought about that having to cover the drugs, vet's time, receptionist's time, upkeep of the premises, electricity, water rates, phone bills, etc, etc, it seemed like a small price to pay. Maybe because we have the NHS for sick humans we assume that the same treatment should be available for animals as well.