With orders of $25 or more, Amazon offers the Cuisinart Prep Board 3-Pack for $8.90 with free shipping for Prime members. That's the lowest price we could find by $5, although most merchants charge $30 or more. They're made of polypropylene, are dishwasher safe, and feature raised edges.
Note that this item is offered as part of Amazon's "add-on program" and can only be purchased with an order of $25 or more. Expect this item to ship in one to two months.