It IS expensive.

It takes a lot of time and patience, too. Some of the cats will be friendly, some very feral.

Even if you use a low cost clinic, there is still the need to house the cat at least overnight before releasing. Very smelly!

Trap, Neuter, Release does not absolve you of the responsiblity of supporting the cats when they are released. Unless the actual owners move and take their now sterile cat with them, they are yours to feed for life. And once you are feeding some of the cats, others will join for the free meal, whether they are ones you've had fixed or not. Be sure you are prepared for this.

Adoption fees for any that you can find families for can help. But for the most part, you are on your own. I can take the tamest to a local rescue/shelter for them to adopt out, because I volunteer for them. Not everyone can do that. (But they don't take ferals or extremely fearful ones.)

Mary