13Deals offers Two TruBamboo 2-Tone Reversible Cutting Board for $14.98 with free shipping. That's the lowest total price we could find for two by $5. It features a removable slotted insert and measures 15.5" by 9.25".
Don't need to stock up? Buy one pair for $9.49 with free shipping. (Firefly Buys via Amazon also offers it for a few cents more with free shipping for Prime members.) That's $11 off list and the best deal we could find.