A while back I pulled a Luck Blade(http://ddowiki.com/page/Luck_Blade) just... completely randomly, on some nothing quest, it just dropped for me, and I was stunned. I had heard these things were absurdly valuable and highly sought-after, but exactly how absurdly and how highly I cannot really say. I've never seen one on the AH and the few I've seen on the ASAH I have no idea what sold for.
I'm also a little curious exactly why they are so highly sought after. Just an ML8 weapon with 3 augment slots... right?