Sory for the bad email address, I edited it a few days ago, I hope it works now.
Anyway - the air dam is real rubber, so parking lot curbs don't phase it. Found it rolled up on a shelf at Dave Turner Motorsports (a local supplier for real race and autocross cars). It comes in a strip about six feet long by five inches wide, cost <$20. Good heavy duty stuff, meant for pavement dragging at elevated speeds, NOT vinyl. Contains a one inch U-shape slot along one edge for mounting onto any metal flange or fiberglass edge up to maybe 3 / 16 thick.
In my case I fabricated an entire subframe from .13 x 1 x 1 aluminum angle, and mounted it under the front fiberglass apron. Took a while but was a fun project. You can't mount directly to the front fiberglass because it's a bit too thin and positioned too horizontal. You need a near vertical mounting surface.