Here is an excerpt from the NH Humane Societies web site that lists the fees for surrendering the cats.
Surrendering Your Pet
First and foremost you MUST make an appointment with a memeber of our Animal Care Staff
Please call: 603-524-3252 x 305 or E-Mail:
adoptions@nhhumane.org
We do ask for a small fee when surrendering your pet.
Cats and Kittens:
From Contracting Town - $25
Additional information can be found here with some excellent advice:
http://www.nhhumane.org/sr-surrender.php