Got mine from a rescue based out of St Clair Shores. They were really easy to deal with and most of the adoption process took place online. I can get you the info if you want.
Currently, any cat over 4 months old is FREE to adopt at the Michigan Humane Society, including all age appropriate shots/vaccines and spay/neuter. I believe anything younger than 4 months is around $25, again including all age appropriate shots/vaccines and spay/neuter.
I have some in my backyard, if you can catch them they're free! The 1 year old mom just had babies this fall and I assume this summer the babies will have babies again. I try to catch them with live traps but the raccoons always run into the traps immediately so it's kind of hopeless.