I haven't looked around this website, but I have used their services.
Spay and Stay
This is for trap-neuter-release programs. In my area, the cost is $25/cat. You borrow a trap; catch a cat; drop it off at the designated place and time; the cat gets vet checked for diseases; gets shots including a 5 yr rabies; gets altered, microchipped, and the ear notched; you pick up the cat and care for it for a few days; then release it back into your neighborhood.
You can read on the web site the benefits of altering feral cats in your neighborhood rather than destroying them.
I used S&S for Roscoe, a mama cat in my neighborhood, about 3 years ago. She's a solitary cat, and had at least 3 litters of kittens in 2 years. I've signed up to do 1 or 2 more cats later this month.