I agree with Liz. I adopted from the SPCA and it was a male adult cat and it was about $100 but they do have discounts on certain days or time of year.
The good thing about getting a cat from the SPCA is they have been tested, they have been fixed and they have their shots. A lot of pet stores like PetsMart and Petco also have adoption days but I am not sure what the cost is.
Our newest member McGee was found in a bush. He was from a feral cat colony and was sick. My husband brought him home for me to nurse. It took a while but he is very fistey. Since we found him we had to pay for all the vet costs and shots
Good luck and if you do get a fur baby please post a picture.