Your conceptual problem: my daughter and I have from time to time found ourselves in that situation with our dogs. Our attitude has been that we have taken responsibility for them, therefore it is up to us to do our best for them even if it means living on lentils for a month.

Having said that, cats are not dogs and seem to thrive best on a more "natural" diet, which may well include raw food (I always cook my dogs' meat, but that is so they don't get ideas)