Cheap alternative to cutting boards
Cutting boards serve two purposes: to keep you from cutting into your bench top, and to keep from dulling your cutting tools. The second reason is the kicker!  You could use a sheet of metal, but your blades would need constant resharpening.

All that being said, I would go to your local Walmart, Target, Fred Meyer, etc and buy a cheap cutting board made for kitchen use.  They work well, and are way less expensive than the ones you'll find at Tandy Leather...