A Roman Writing Tablet available at Amazon for around $67.00. I wish I could afford one, but first I have to pay some more taxes ... and even then it's a bit steep for something I will probably never use.
I do like the format for note-taking, however. What you see is a diptych, formed of two pieces of wood. For heavy note-takers there were triptychs (made of three pieces) and others with even more pieces.