Most shelters have the "Friends of " organization that runs things. They usually have certificates available for so much off for a spay (I got $25 off from a local shelter group). Also, there are programs/events for low income families to get free or reduced spay/neuters. Allot of times they are associated with moble clinics. Rescue groups in your area check them out. I would first contact your local shelter they should be able to direct you to various programs.