We have a multi-cat household.  I found if I go to K-Mart
first, then Walmart, I can buy their large plastic storage
boxes and use them as litter boxes.  The price is a fraction
of what you would pay in Petsmart or a pet store for a litter
box.    As far as food and litter go, Petsmart and other big
box pet stores are ok if you buy their largest sizes, otherwise
go to Walmart.      shop, shop, shop