I love my chins! I have 2 a boy (who eats like it is the only food he will ever get) and a female who is timid. I think it is relatively cheap once you get the chin and the cage. I am a college student and I have 2 of them. I buy this very soft, woodchip bedding from Walmart. I have to change it weekly but it works for them and they love it and for a huge bag of like 20 lbs it is only like 7 bucks and it lasted me about 2-3 months! The food is about 10 bucks for about a 2 month supply. I get my petfood from petco in bulk.
I would say for my 2 chinchilla's it has cost me about 10 bucks or so a month. Unless I decide they need more toys. They have their own room so they really have enough!