Our supplies stay pretty stocked when we are willing to take opened craft supplies. It's easier for parents to give away something they aren't using and have already spent money on. Its harder for parents to make a special trip to the store to buy you something and spend money on it.
We love standing in the supply room and looking around discovering what we can make with our students. Its also pretty awesome to see a parents face when they realize we have turned their old junk into something amazing their child has created, that they can keep forever as a special memory.
Its rare for us to find a craft, science experiment, or recipe we want to make with the kids and not already have the ingredient or supply on hand. We credit this to all our stuff and junk collecting! We like to stock up! Because of Mrs. Layne and her superhero organization skills, each thing we collect is carefully put away and organized in an amazing system. We don't know what we would do without her!
So my suggestion to you is get out there and ask parents to clean out their junk drawers and donate it to you! Happy collecting!