Nipomo Cat and Dog clinic will do it for $20
To get them spayed or neutered go to your local vet. Sometimes local pet stores will host a spay/neuter clinic for discounted rates. Depending on the vet and whether it is a spay (more invasive) or a neuter the prices can be $50-150 per cat. If they are feral then they will probably need a number of vaccinations as well.
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