Right now I have 3 cats that don't have issues with crystals; but I used to have one that did. It can get expensive, you're absolutely right. To me, the life of the cat was worth the cost. (very friendly, outgoing, not shy with people at all, full of personality)
That being said, the kitten shouldn't be eating adult cat food yet. Purina makes 3 different "levels" of food: The cat chow, or kitten chow, is the cheapest. Then there's Purina One, which costs a little more than the cheapo cat chow, but comes in formulas that are supposed to be for situations like hairballs, weight loss, and crystals ("urinary tract health formula"). They have kitten food too. The primo (most expensive) Purina food is Purina Pro Plan. That also comes in formulas, and also has a type meant for cats with crystals. And they too make kitten food.
All three "levels" make both dry and wet food.
With the 3 cats I have now, I've been feeding them a mix of Purina One urinary tract health formula and Pro Plan urinary tract health formula. None of them so far have had crystal issues - and the oldest is now 11.
Hill's Science Diet also makes food for situations like hairballs, weight loss, and crystals.
You could look at websites for places like Pet Supermarket, PetSmart, and Petco to compare food prices. Also, the Purina chow level and the Purina One level are carried in many supermarkets.
Hope that helps!