That pic is of the SAS-M7 No-Ban. It's not a limited run, but they do make a lot less of them than the standard rifles.
The underfolders that were limited runs were the Classic series, and the A1 underfolders. The very first underfolders that they made after the ban was up were limited also, they are the same as the SAS-M7 except they don't have threaded muzzles and they don't have bayonet lugs.
You still need to jump on one. One of the big reasons they are more money is tha the receiver for a milled underfolder vs. a milled standard is more expensive to make and they don't make many of them.