Hey Grateful Bear! I helped a woman down in Trenton with a similar problem. The townhouses were cracking down on people feeding the strays and ferals, and she had four she'd been caring four. I used this link: http://www.pets911.com/organizations/organizations.php
and just started an e-mail and phonecall campaign. I found a kind soul who helped her trap the cats and that person also took responsibility for having them spayed/neutered. In fact, she also found them homes. I hope you'll be as lucky as I was (she did it on her own time, not as part of an organization, so I can't share that info, sorry!).
NJ does have a low-cost spay/neuter program. It requires finding a vet that participates and filling out paperwork. I think a neuter is $35, and I don't know what a spay costs. Hit the yellow pages for vets in your area!
Good luck, and keep us posted!
And THANK YOU for being such an angel and doing what you can to help these cats! If nothing else, just having them spayed/neutered will help prevent more unwanted kittens in the Spring, and that truly is an act of kindness and mercy that is worth doing! Also, you can call around to local shelters to see if any of them could lend you a trap. The link I provided may help at least find a trap you can borrow.