I just wanted to say a couple things.
I have been trying to get a set of these for a while, and bought some off of ebay a little while ago. They were claimed to be OEM headphones, and the seller assured me they were authentic. However, they are fakes. Just like the ones linked to on
http://www.foster.co.jp/products/headphones/382326.html are fakes. You can tell by the mini jack. Real CX300's have a 90º mini jack, while these fakes have a straight mini jack. Not only that, but the minijack is not mated at all with the cord. (See the attatched photo.)
The sound quality of the fakes could be worse, but it isn't even as good as my $10 sony's. All of the midtones are very muffled, and can't be recovered through an equalizer. Highs are poorly managed and shrill. (Just trying to listen to Bring Me to Life by Evanesence is a painful experience.) There is plenty of bass, but it is very boomy. (Kinda reminds me of Logitech speakers in that repsect. Plenty of bass, but not well defined.)
I am hoping to get some real ones within the next couple weeks though. I'm just going to keep looking for a good price, since the best that I have found so far is about $60 once you add in shipping.
And sorry about the bad pic, but it is the best that I can manage in the lighting I am in.