I feel pretty lucky in this regard, in that I’ve got family members who work at a grocery store, and they let me bum off their employee discount. It’s only good for store-brand items though, and it only works while they’re off the clock, so it takes some coordination for me to use it. Stacks with coupons though, which also helps.

Buying in bulk can absolutely be helpful, if you can shop at wholesalers or warehouse clubs, and take advantage of coupons and sales. Wouldn’t recommend doing this for perishables though, if you’re only buying for yourself. Might also be annoying trying to find space for everything at home.