I saw this bath toy bag tutorial from Make It and Love It on Pinterest the other day and loved the look of it. However, instead of going to a fabric store, buying mesh and ribbon, possibly going to another store to buy suction cup hooks, and later spending precious nap time sewing the thing, I went to my basement.
I had two mesh laundry bags for delicates (now I only have one) and a few leftover suction cup hooks in a package (that's how I hang my bath poof). If I hadn't had the supplies on hand, I suspect one could find them at a dollar store for a whopping $2 investment, far less money than baby store bath toy bags and less time/effort than the DIY version.
Whatever the cost, it's worth it to have a tub ledge free of boats!