You should be prepared for long hours of hard work in the studio, and that means you will probably get hungry. You have to budget for snacks as well. You can also bring something more substantial to make in the studio, like bagels and cream cheese. It depends where you are also. You should plan to buy drinks too.
Beer is a perennial favorite.
Coffee is also popular during long hours of recording. Mark likes o.j. For a long time I drank Classic Coke, as it was known back then. When we did the Air Miami record, we drank Jagermeister. Soothes your throat.