i get the bulk litter refills from petco. its not the best litter but it clumps and controls odor well and its inexpensive because you can refill the 30lb container for about 6$ and that lasts me like maybe a month for 2 cats, it depends how many times I do a full clean out of the boxes that month. I don't find it necessary to completely change the litter often. once or twice a month is good. my cats are shy so having something that smells like them in a room is very good for their confidence.
On the other side of the bulk litter I was thinking it would be better for the environment because I reuse the same plastic bin to get it, but then its clay litter so Pfft not great and well how do they receive the litter (probably in plastic) so im sort of dumb for thinking it was a better choice environmentally.
I couldn't tell you for food. I have been trying to get them to try different brands and the prices are all over the place because what I have been spending isn't accurate to what they have been consuming.
I spend about $100 on food every 3 weeks. The dry is about $26 and I buy two kinds of wet food which make up the rest (one is almost $47). I buy 3 small bags of Fresh Step litter every week. No idea how much that amounts to but probably not even $20.