If you want a constant source of free paper I will let you in on my secret.
Okay, does everyone know what "rack cards" are?
They are the card stock that is used to advertise the newspaper in the
fronts of the paper machines at markets. All large newspapers use them. They
change them often for various events and promotions. If you call the
newpapers and ask for the distribution manager your halfway there. If the
distribution manager is a friend of art education they will set you up with
a constant source of rack cards. Sometimes they are the old ones they take
out, sometimes they are brand new. They are nice white oaktag on the back.
And 14"x20" is the perfect project size. I have used this source for 12
years. It saves a substantial amout of our budget for other fun stuff.