Where to buy art supplies cheap. Try a good will or other thrift shop.
I've never seen art supplies in a thrift shop. Ever.
I am a Thrift Store Shopper and I even used to work in one. Usually almost none are available in the thrift store. I only found ONCE some oil art paints when I was working there. Other times, none. Usually they are thrown out. The stores prefer glass, dishes, applicances such as coffemakers, toasters but no microwaves allowed, no TV allowed and no computers allowed (in old days, it was ok to donate and sell them but not anymore due to the deposal fees posted by the State of NY (perhaps nation wide too). Clothes, decors, DVDs/VHS, books, steros/Radios, flashlights, bags, shoes.. baskets, hair dryers,.. that is about it. Oh yes, of course, furnitures and fabrics but no mattresses due to health laws. That is all. Artists usually throw them out because paints get hard and dry in tubes. For brushes, it gets fallen apart.. for canvas.. never seen one! Perhaps they are all used up except for already painted pictures that can be sold. Sorry to burst your bubble, no art supplies in thrift stores. Maybe flea markets? I doubt it either.