They sell them at Upland Feed and Fuel in Upland, California. But I doubt you'd want to drive that far to get it.
I've ordered three of them on ebay and they took only a couple of days to arrive. I have one in the bedroom, one in the living room and a third for travel/emergency use. All are the small size. Getting ready to order the largest size so Tallulah has room to play outdoors when I can't keep an eagle eye on her.