This is one of my all-time favorite fragrances. LIDGE is Not For Sale in the US by Guerlain (not sure why). You may find many sites that advertise it, but there out of stock or at least have been for a long time. There are many legitimate sites, but as far as LIDGE is concerned, it's a "draw item" to their store whether they have it or not.
You also may have seen LIDG (not extreme version), which is also very good but is much cheaper.