School supplies, really cheap whiteboards
So apparently if I don't care about it being in a frame (I don't) I can get a 2'x3' whiteboard for just over $6.
Before I knew this I was pricing frames for posters as an alternative, but these are the same size and at a minimum 3x as cheap.
Before I pay out of pocket I think I'll see if these are on our approved vendor list. My principal has paid for room improvements before, but if they aren't on the list it's a no-go.