Do you like juice?
The water where I grew up I swear tastes
aweful, even after filtration, so its hard for me to drink it straight. When I realized I didn't get enough hydration when I was drinking just water, (which doesn't help with my migraines) I switched to a low-calorie juice and diluted it. I usually get by with just a splash of juice, but it would probably be a decent place to start weening yourself off sodas.
I'd suggest cranberry juice, but if you can't stand that, go for a blend of cranberry and some other fruit juice.
Cranberry juice is good because it helps to prevent urinary tract infections, which are linked with kidney disease. (And if you're having issues with sugar, making things easier on your kidneys can't hurt)
Also, frozen vegetables aren't usually
that bad, price-wise. I'd suggest getting a family sized package of Brussels sprouts and eating some frozen for a nice hot weather snack!
Also, beans are surprisingly nutritious. They are a carb, so that's important to keep in mind at meals, but they're dirt cheap. They tend to have a lot of sodium when canned, though. Again, frozen is your best alternative to fresh.
Also, if you like chewing, go for sugar free gum. When you can find a good sale on the larger packs, its pretty economical, especially when considering that its keeping you from snacking on something that's just as costly. Trident, Orbit and Extra tend to have the best longevity per pack for its price in my experience.