I think Theohazard is right- you have a very specific desire and it is something that is likely only made in small batch numbers. In this environment, most everything is flying off the shelves.
You may have to special order it... have a local shop order one in. You may even have to wait for Sig to make a batch or for a distributor to get one in. Calling Sig's own shop may also be worthwhile- you'll probably pay more for the gun and then have to pay shipping/transfer, but if you really want that particular model, that may be the only route.