We had a launch offer when KFLL was released, for users owning the other sceneries, it lasted about 1 month after the released date.
The thanksgiving offer has expired now so, I'm afraid the only way to get KFLL at discount, is to use the "Cross Sell" offer, explained here, which is always in effect:
http://www.fsdreamteam.com/forum/index.php?topic=2159.0However, if you already have all the other sceneries, the only discount you might get, it's a 25% discount on XPOI, if you buy it together with KFLL.