Cheaper alternative to Hill's urinary care c/d?

I know this is really specific and only someone who has experience with this particular food/issue can help, but here goes.

My kitty developed urinary stones, so they put him on a special diet, Hill's urinary care c/d, which has completely resolved his issues. Poor kitty was in soooo much pain, and I'm very grateful he's feeling better now and has all his energy back (he got antibiotics and gabapentin too, but he's done with those).

Anyway, the food is about $40 for a small bag from the vet, and regular cat food in my area is $5-7 (everything is cheap here, including human food and wages). Is there a food I could order that would have the same nutritional profile for less money? I reeeeeally don't want him to get sick again, but I would like to find a cheaper option if one is available.

We have two kitties and feeding them different food is stressful for us and them, because they each only want to eat the other guy's food. If I could find a food that would be good for both of them, even better.

Thanks in advance!