It's $US50. But in an age when Apple was just selling fanboys Livestrong bracelets for $US30, I don't think we can complain about that point too much.
Have you tried Air Display yet? It's wonderful. The only real flaw with the app is something you realise about one minute into its use: You're gonna need a stand to use your iPad as a second monitor.
Innopocket's HexaPose stand completely obliterates that issue with utter design overkill.
Their solid aluminium and polycarbonate stand mimics the iMac right down to the hole for cords, all while supporting portrait and landscape configurations with three angles of tilt apiece. The company hasn't listed a weight, but the HexaPose looks solid and poised - plenty to anchor your iPad on your desk with prominence and security.
I don't know much about Innopocket's products, but assuming the build quality is up to snuff, this could be one excessive accessory purchase worthy of excessive accessory purchases. [Innopocket via Geeky Gadgets]