This is what I did with 3 roommates in college. We saved a ton of money that way.

After college, I only had one roommate and Costco didn't work as well. The quantities for certain things are just a bit much. Buying 36 eggs for 4 adults made sense. Buying 36 eggs for 2 adults... not so much. I ended up going to Costco for toilet paper and gas, and that's it.

To this day, I'm still the "spouse" on one of those college roommates' costco memberships, LOL.