I save money, by ordering cheaper alternatives. For watercolors, I buy the Prang classroom sets. The students kind of scoff at them at first like, "We used those in Kindergarten.", but then they realize they work pretty well. I originally used some tube sets, that were in the room, when I got here, but found that students treated them like acrylics.
I would love to have Prismacolor pencils, but yeah, they are pricey. I got a Blick classroom set this past year. They are OK, nothing great.
I wouldn't get rid of sketchbooks. The spiral bound ones I get, are only about $3-4. It's not Strathmore paper or anything, but works well. I had the students make their own sketchbooks one year. We took our standard drawing paper, three-hole punched it and used those brass fastener things.
The two biggest expenses I have are glazes/ underglazes and photography supplies. If I need to cut back, I can always reduce the number of glaze choices I use.
First day, with students, is tomorrow. Time to get back into the swing of things. I may do the pinch pot thing, in my clay class, the second or third day, so the students get a feel for the clay.