Bladder infections can't be treated without antibiotics to get rid of the infection. Most cats do well with penicillin, which is a broad spectrum antibiotic. My suggestion to avoid the vet bill would be to go to a Tractor Supply Company or local feed and seed store. Get a bottle of liquid penicillin that they uses for horses and cattle. The correct does would depend on how much your cat ways. If under 10 pounds, get a human baby medicine dropper (wash one out really well out of a infant Tylenol or mylicon bottle.) Give the cat .5ml (the first line on the dropper) of penicillin 3 times a day for 10 days. The bottle of med you have to keep in the fridge after you open it. You will have way more than you need. The med will keep for up to a year, though. Sometimes longer (read the expiration date.) Also you can get food that helps maintain their urinary tract health. I'd get some and feed it to the cat all the time. The medical will cost you about $25.00. A vet bill will cost over $100.