Fabric boards from Home Depot
Ok so you have to cut yourself.. But I found that plastic board in a (I think it was)4x8 sheet for around $11 . Way cheaper if you cut your own.. at 6 inches x 10 inches fabric board . Thats quite a few. i know you lose some inches with the cutting but thats about 72 boards per sheet.. 15 or 16 cents each!!!
I didn't pull it out and I just saw the price on the sticker near the floor. So I am hoping thats what it said. I am happy with my comic boards but for those that aren't I figured this would be cheap way have having something a little sturdier.