Quite oppositely to what his name suggests, this seller NPC is somehow very generous : he simply "offers" some of the best nano crystals available ingame for few specific professions, previously very hard to get (hours of static farming and/or incontrolable GMI prices) !
But you'd certainly have to pay the price and not be too tightfisted with him, as his fees are going from about 55 upto 550-ish Millions of AO credits - with a 1500+ computer litteracy basis considered (meaning that our smartest traders can bargain a juicy discount ...).
Oh, wait : before you rush like crazy up in Pandemonium, beware : this picky Shade might simply refuse to speak with you and, instead of showing his selling list, reply quite rudely with a "Leave me alone, newbie! What part of go away did you not understand?". SO let's first see how to avoid that.
To proove him you deserve his treasures, you must present him with the entire collection of your own side Garden AND Sanctuary keys together, meaning 11 in total !