If you live in New York City, there are several ways you can get certified to do TNR. Once you take the workshop and receive your certificate, you can sign a Rescuer Agreement with the ASPCA to use their spay/neuter services. There are also several other clinics around town like Faithful Friends who offer discounted spay/neuter for the TNR certified.
You can also borrow traps and equipment from Neighborhood Cats or the ASPCA, and you’ll be eligible for discounts with several participating vets! It’s so easy to do, and it never expires so any time you find a cat who needs fixin’ you’ll be able to do it affordably. See links below for workshop info.