There are substantial financial benefits to spaying and neutering your pet(s):
Sterilization eliminates or reduces the urge to run away and the cost and worry of injuries and impounds. If you have ever had to go to an emergency hospital because your dog was in a dog fight, you are most likely aware of how costly that can be. And if you ever went through the misery of a lost dog, you know that in addition to the trauma to you and your family, advertising and impound fees (the fees you pay to take your dog home from Animal Control) can be considerable.
A male, sensing a female in heat nearby, can break down doors and jump fences in his desire to mate which can be very costly to fix. If that female dog had been in your car while in heat, male dogs may scratch at it and damage the paint in an attempt to get in since long after your dog was taken from the car, the scent remains.
Sterilization eliminates the worry, hassle and cost of litters. To properly raise a litter of puppies or kittens, they must be cared for until at least 8 weeks of age which involves the cost of food, inoculations (shots), gates and other containment items, toys, etc. - not to mention the time that is required or the vet fees you may end up paying if there are complications before, during, or after birth.
Spaying and neutering reduces the costs resulting from pet overpopulation such as those incurred by animal control agencies and law enforcement. It frees up public funds for other essential services like police, schools and health services. Without it, you pay with your tax dollars and the animals pay with their lives!
Sterilization cuts the cost of dog licensing by more than half in most areas and in some areas, the first year is free; the reduced dog license fees alone will offset the cost of the spay/neuter procedure.
The alternative is just not worth it! Animal overpopulation has a price none of us can afford.