That would help the community a great deal, like im all for buying for authorized sellers but if u can get it cheaper why not right ( obviously if u see it for like 100$ theres a problem)
The main difference between the Brown and the Black version is that the Black version also has a QR code on the side for verifying authenticity by going to this link and entering in the information here:
http://qr-sennheiser.com/index.php?id=5&L=1&id=5
There is also a video showcasing it here:
http://www.youtube.com/watch?v=XjQ299zz4qo
Here is the pictures of their boxes.
Brown Version:
http://i.imgur.com/W843CZW.jpg
Black Version:
http://i.imgur.com/2unOjSo.jpg
Also here is another picture from a fellow member:
http://www.head-fi.org/t/644988/sennheiser-launches-sleek-momentum-black-headphones/15#post_9156718
Also another view of both boxes:
http://canadahifi.com/wp-content/uploads/2013/04/Sennheiser-Momentum-Headphone-Custom.jpg
Black Version Box Side (note the QR Code):
http://techwelike.com/wp-content/uploads/2013/06/Sennheiser-Momentum-05.jpg
http://www.flickr.com/photos/91389588@N02/8456667348/?rb=1