I rehomed a cat once. I listed it on Craigslist with some really cute pictures. I got a lot of responses. Just charge like $25. There are a lot of sick people out there looking for free cats to harm, so you need to charge something, but not too much. If they are up to date on shots, tests, neutered/spayed, etc., make sure you advertise this. This makes the cats more desireable to people. You can also offer to give away their toys, litter box, etc. with them. Try to get them a good home together, so at least they have each other. Also, I put in my ad that I was willing to deliver the cat. This way, you get to meet the family and new home. Also, I was willing to drive an hour from my home to deliver the cat to a really nice family. The family didn't have reliable transportation, so they probably would not have been able to adopt him if I didn't state in my ad that I would deliver the cat.