I'm sure there are things you can do OTC to lower the pH, but I disagree that they're pushing the expensive food just because they want your money.

There are no other foods on the market that can put on their label that they are a prescription food for a medical condition. Those prescription foods go through a much more vigorous testing process than your normal commercial diets to, because they have a lot more standards to live up to. And they do work, but you have to be very strict about only feeding that specific food.

If you would like an alternative to the prescription diet, I urge you to contact your vet to talk about other options. Your vet is the only one who knows your pet's condition, better than any of us. Plus, there are many different stones that form in different pHs, so your vet will be able to give you a better understanding of exactly which "stone" you're potentially dealing with and what you may be able to do to help prevent their formation.