This Chalk board paint is $6.99 at Joanns but I used a 50% off coupon on it. boooyah! Cheapo!
I had some extra bead board from my kitchen black splash it is about a 9x10. Put three coats of the paint on and let it dry then glued (with wood glue) to the back of this frame. (Below) I wish I had a cute, more interesting frame but I have used all mine. I painted the frame an antique white.
tah da! it changes with every season. Sorry for the ugly writting I only had my kids sidewalk chalk. It's fat and chunky and hard to write with. But your get the general idea.