There is a cupboard just inside the art room door with old tempera and
stuff that is avialable to anyone in my school. If someone is begging
for some expensive material, I explain the budget, (less than $1.50 per
student for the year) and say I am glad to share if they will commit in
writing to replace the materials borrowed.
After re-reading BluesTruth's post, I also had another idea... print out
what was said in the email and post it in the teachers lounge.