I live in Ontario, Canada. The Canadian Tire stores have great prices on litter boxes, litter, food, etc. I also go to PetValu and Global Pet Foods.
I used chewy.com for most products but I buy my cat food elsewhere I also recommend chewy.com they have the best prices and low shipping cost cost and I think if you order $50 or more shipping is freeDo you have a Tractor Supply Company near you? Their litter is about the cheapest I've found and works really well.
I get my dry cat food from chewy.com, delivered on a regular schedule. There's is a discount for subscriptions and free shipping over a certain $ amount. The cats love the cardboard shipping boxes and packing paper. No need to buy expensive toys or scratchers.