there are many shelters that do spays for next to nothing and some that do them free. You can get vouchers to get it done at half price as well. You need to get on the phone and call around to all the shelter and find out when they have their spay and neuter clinics and how much it will cost. In all honesty if you could not afford to spay your cat you maybe should not have gotten her and you most definately should not have let her outside where she could get pregnant.

I am not trying to be rude or abrasive to you but your cats health is at risk by being unspayed and having babies. There are so many things that can go wrong with a pregnancy and birth if you don't have the money to get her spayed that means you don't have the money for an emergency if it should arise throughout her delivery.