Should I let my cat have kittens?

I had an interesting conversation last week with a lady who has a 6 months old kitten. She was trying to find a charity that would pay for the spaying operation, and was telling me that she couldn't afford the bill. She seemed to feel that it was her right to get the operation paid for, and the charities should be doing this. She told me that if one of the charities didn't help her, then she would just let the kitten get pregnant and have a litter, as she could easily home the resulting kittens to friends.

If she chose to do this, the result would be
1. She would have the cost of giving the mother cat extra food whilst pregnant and lactating.
2. She would have the cost of feeding the kittens until homes are found for them.
3. She might end up with veterinary bills if the cat has problems in delivery, or if the kittens need care (unless she decided she couldn't afford it and just stood by while they suffered)
4. By producing more kittens for her friends, she is depriving a kitten or cat that is already desperately waiting for a new home, from getting that home.
5. Either she lets her cat go on producing litter after litter, with all its costs, or she ultimately has to get the cat spayed and pay the bill in any case.
6. Allowing her cat to come into season, will result in males for miles around coming to mate, some of which may carry diseases that could be passed onto her cat - resulting in suffering for the cat, and more vets bills.

Wouldn't it be easier, cheaper and kinder just to get the cat spayed in the first place? And as a cat rescue organisation, should we be using the money that people donate to us to care for cats, or to pay the vets bills of other people who don't want to use their own money? I know there are cases of real hardship, but surely, if, as individuals, we take on the responsibility of looking after an animal, we should be prepared to pay out occasionally, and to budget accordingly.

I'd be interested to know what you think.