Get low-cost neutering by visiting the ASPCA website and contacting one of the low-cost neutering clinics listed near your location. As of 2015, the ASPCA maintains an up-to-date public database of locations where you can find free or low-cost neutering services for dogs.
ASPCA.org lists veterinary clinics that perform low-cost spay and neutering under the general pet care section. Clinics throughout the entire United States are listed. They also list programs that provide spay and neuter assistance or referrals in case a nearby clinic is not forthcoming.
The ASPCA runs a mobile clinic, consisting of a fleet of vans that can perform spay and neutering on site. These mobile clinics are not available nationwide, but they do provide low-cost neutering throughout New York City.