help neuter a feral cat colony

as some of you know I've had a feral cat colony take up residence behind my house. I'm trying to catch them and get them fixed before it spirals way out of control. i finally got permission to place traps on everyone's property they hide on. currently there are 15-20 cats most of them kittens. this is extremely expensive because most is coming out of my pocket. I'm going to be doing everything through tara van. if anyone can donate anything it would greatly be appreciated. all extra funds will be donated to local tnr groups.