Hey, I found something that I thought you guys might find interesting. I've been searching for "sand tracks" for awhile, and the closest I've found are absurdly expensive ones from Britain, or "waffles" - also absurdly expensive. I just found a military surplus place that sells them (used) in several different sizes (from 16"x5' to 20"x11'11") starting at ~$17.
http://www.whiteowl.com/equipment.html (Landing mats)