And as I recall so many complained about the price. They are by far the best investment I have made.
To save on the wear & tear I now accompany them with Wizard's Dungeon Tiles that are pasted on with poster putty, and also use jenga blocks (3"x1"x1/2") to give 3D effects such as stairs, platforms, columns, walls, etc. It save on erasing too, as I only draw secret doors & rooms on the tiles themselves.