This is probably not what you want to hear, but.....I have 13 cats (only 2 diabetics) and all of them eat canned food, and really when I did the math, it still costs me about the same to keep them all on canned than it does to have the non-diabetics on dry. Now with 13 they don't eat the top of the line canned, I feed either Special Kitty (Wal-marts house brand) or Friskies and I get the 13oz cans. But where I see the savings is in what I'm not spending in litter, and vet bills. Since their bodies uses more of what is in the canned food, there is less out put in the litter boxes, also I have one guy that I have struggled for years with his allergies, until switching everyone's diet to canned, now he is off the allergie meds, no longer going to the vet for antibotics for infections caused by those allergies and is a much happier cat.
Everyone also shed less now that they are on canned food, so there is a savings for me in time as well, because I spend less time cleaning fur off everything. Now they still shed but it is more seasonal now than all the time. So I have less to clean out of litter boxes, less fur all over the house, no more UTIs and don't have to pill one everyday just so he can keep the fur and skin on his face. As well as having one diabetic in remission and the second one working really hard at becoming diet controlled, she hasn't made it there yet but her insulin has gone down from 1.25u BID to a mere .25u bid. And I don't have to worry about my diabetics getting into the dry food.
Now if you do need to switch the non-diabetics to dry food, I would stay away from the cheap stuff and feed a high quality one, which isn't going to be cheap, but it becomes one of those things of weighing the costs upfront for the food to the costs down the road of paying a vet to handle the problems that dry food leads to.
Again, probably not what you wanted to hear (sorry)
Mel, Maxwell, Musette & The Fur Gang