Yes, Jaime, I'm definitely an iris lover - both the fragrance and the flower!
I believe most of the astronomical price is due to the ageing process, and not from the scarcity of the raw material or the harvesting effort, as it is with rose and agarwood. It literally takes years for the iris root to develop its aroma. For better or worse, a method for accelerating the ageing process was developed recently (since 2000 or so, I think), thus the use of iris in a variety of affordable fragrances. From Luca Turin's Winter 2008 newsleter:
"French raw materials outfit Biolandes has figured out a way to make iris root age fast, and thus lowered the price severalfold. As a result, everybody from Chanel downwards is doing an iris."
I suspect the accerlated iris product is only a pale imitation of the best Florentine iris butter. My favorite takes on iris would be (in order of personal preference) Bois d'Iris, Iris Silver Mist,L'Artisan's Iris Pallida, 28 Rue La Pausa (only because it's a bit too feminine for me), and Dior Homme.