Horse Stall Mat as Exercise Mat

I've seen it suggested in various places that horse stall mats make great, cheap exercise mats. Looks like the rumors are true! Tractor Supply Co. carries a 4' x 6' stall mat for $40. It's 3/4" dense rubber, and really heavy. If you want one, it's entirely possible there's a Tractor Supply Co. store near you. Transporting it's not too big a deal; it rolled up (although not real compactly) and fit in the back of my Subaru Outback easily (with the seats down).