Affordable Alternative Urinary Food

My mom's cats had trouble with crystals when they were younger (they're five now) and they've been eating the C/D prescription food ever since.
I recently added canned food to my cats' diet and when I found the Friskies Special Diet food, my mom happily added that to her cats' regimen.

The problem: Friskies is discontinuing the Special Diet line. What other affordable options are there for a urinary food? Any other recommendations in place of the C/D kibble?

Any commerical canned food will help, really. You don't need a specific urinary formula at all. Or dry food. Dry food is why many cats get urinary problems in the first place. Some dry food in the diet is ok if you must feed some dry but balance it out with plenty of canned food with extra water added.

The regular Friskies is fine to feed.

Here are threads on the same topic:

http://www.thecatsite.com/t/301313/wet-food-for-cat-after-uti-crystals

http://www.thecatsite.com/t/300481/science-diet-c-d-dry-vs-wet

http://www.thecatsite.com/t/254489/alternatives-to-expensive-urinary-so-food

http://www.thecatsite.com/t/298749/best-canned-food-for-cats-prone-to-urinary-blockage-crystals

http://www.thecatsite.com/t/182964/friskies-special-diet-canned-foods