Just found this and thought it looked quite useful for transporting when gaming elsewhere and quite well-priced. It's available for £22.50 at <a href="
http://www.waylandgames.co.uk>
Wayland Games[/url] so not overpriced and easy to use with your existing tabletop grass matts.

The sale blurb: "Covered in hedgehogs and tripods, the beaches of Northern France were a treacherous and formidable landing site - and with strafing machine gun fire, near-constant shelling, and a literal wall of Germans standing before them, Operation Overlord saw waves of Allied infantrymen make their way across this deadly battlefield. This pack includes one full-colour 4in/120cm x 16in/40cm vinyl Beach Landing Mat."

What do you think of this mat?