I got my 1.25" x 12" x 14" maple checker cutting board for $73
here. The main cutting board page can be found
here. Mine's 5 years old and is weathering very good. A variety of wood, custom sizes, and board designs are available. Free shipping but I'd expect a 24" square board will cost you at least $200 with the minimum 1.25" thickness, much more if you're looking for 2" thickness.
Cheers,
Robin