Why do rescues charge so much?

As a rescue, and being friendly with many others in various rescues, one of the questions we receive most often is why do we charge "so much" for our dogs. We hear that someone could purchase a "registered puppy" for the same price. We also hear ideas like "the dogs shouldn't cost so much, they are rescues". So what is the basis for our adoption fee? It is this.
Every dog we take is spayed/neutered, fully vaccinated, tested for heartworms, tested for intestinal worms, and microchipped. If they have any health issues, they are treated for such. They are then placed into a foster home where they receive flea/tick prevention, heartworm prevention, high quality food, toys and treats, attention and training. All of this costs money. While some veterinarians may give us a small discount, veterinary services are by no means free.

Our average cost per dog is over $500. Why? Consider this:
Spay/neuter average cost $150
Antibiotics/pain meds for spay/neuter $60
Vaccinations for rabies, DHPP, and bordatella average cost for all $65
Microchip average cost $50
Heartworm test $30
Intestinal worm test $30
Most dogs have some form of intestinal worms at intake, treatment average cost $45

For dogs with heartworms, average treatment cost $500

For dogs with any other ailments, treatment costs can range from $30 antibiotics to $1500 teeth extraction and root canals to $3000 intussusception surgery and treatment.

As a rescue, we do not turn down dogs due to medical considerations. A good dog with a good temperament deserves a chance at a happy life.

While in foster care, flea/tick prevention is $5 per month. Heartworm prevention is $6 per month. These are per dog. We average 10 dogs in foster care at any given time. We also help our foster homes with kennels, food, treats, and toys when needed.

Considering all of these costs, and that 1/3 of our intakes come to us with heartworms, the real question is How Do We Continue to Operate with an adoption fee of only $350? We beg, we plead, we have wonderful supporters who donate to us. We put our own money into the rescue when needed. We apply for grants, though we rarely get them, and we apply to other organizations who partner with rescues by providing funds. We host fundraising events, attend other events, and beg and plead more.

Forgive us if we scoff when someone asks "why are your dogs so expensive". Our dogs are priceless. It's the cost of caring for them that is so expensive.