I love Jeanie's idea of getting the neighborhood together and neutering those Toms ... the benefits are many, and the cost for neutering a male is normally lower than for a female. I can just see your community getting together and working towards this very important goal. It would be a great Summer project for the kids since school is almost out. Have them make it their "What I Did This Summer" report, and take pictures, explain the process ... oh forgive me, I do ramble on so when I get excited. *grin*
As a suggestion, maybe you could call your local ASPCA or Shelter and ask if there is a low-cost spay/neuter clinic anywhere in your area. Additionally, it might not also hurt to speak frankly with your own vet, tell him/her the circumstances, and ask if he/she would be willing to discount the fee a bit. My guess is that your vet would be happy to help. So would I. If you have any questions, or I can provide you with any other assistance, please do not hesitate to contact me.
Regarding the missing kittens, is there any update? Have you found them yet? I just hate to think of the possibilities, and the thought of them needing their mommy concerns me.
Best of luck and please let us know how you are getting along,