Alley Cat Allies is a national organization that helps areas find solutions to their feral cat problem. Check them out. Maybe with their help you could get your city/county to help.http://www.alleycat.org
For example: the spay/neuter clinic I work at has a "deal" with Oakland County. As long as the cat lives in the county, they fund the majority of the s/n cost. Feral cats in this county can be altered, Rabies vaccinated and ear tipped (for identification) for $10 per cat the "caretaker" brings to us. The city of Southfield went one step further and will reimburse the caretaker the $10 they spent if they bring in our receipt. And if I'm not mistaken, Alley Cats helped us make this happen.
Another site with good info (I know they are in MI) and worth reading is http://www.carolsferals.org/
I know its hard taking anything to a shelter, but think on this...
If any of those kittens were female, they would have been pregnant before this summer was over. And in all likelihood, the mother of the litter you had to surrender is pregnant again. Cats can get pregnant as early as 4 months, and can have between 3-4 litters a year. I'm not making this up, I have seen these very things first hand and frequently. 1 female cat can be responsible for (through her own and her offspring and her offspring's offspring) AT LEAST 90 more cats PER YEAR.