It looks like the uber-sexy Aurora 224,  an open source USB powered multichannel DJ mixer, is DOA. 
According to a post by Mike Garbus in the Aurora forum:
We’ve got some unfortunate news. Due to a lack of interest we won’t be able to sell aurora units at this time. We needed to get at least 50 people [...]

The Aurora 224 - a USB powered multichannel DJ mixer designed by Matt Aldrich, Mike Garbus and Maro Sciacchitano - is now available for purchase as a kit.
The device features two linear channel faders, a single a/b crossfader and eight backlit buttons. Twenty four backlit knobs allow you to control effects. It’s open source - [...]

Aurora is an awesome open source usb powered multichannel mixer in a typical DJ form factor. Aurora is designed to easily integrate with your favorite midi compatible software.
The device features two linear channel faders, a single a/b crossfader and eight backlit buttons.T wenty four backlit knobs allow you to control effects.
Aurora, unlike most midi controllers, [...]