I've seen them in Best Buy, Circuit City, Comp USA, Micro Center...
I would say that the Copperhead has come a long way in terms of driver/firmware development since it first debuted and it is pretty awesome as it is right now, I like it better than the Habu despite the Habu's superior button placement (of course this is all my opionion, the symmetrical design of the Copperhead allows for two thumb buttons whether you use the mouse with your left or right hand, the problem is that using those "thumb" buttons opposite your thumb, it isn't practical and thus the 7 button mouse in practical use is only a 5 button mouse in the heat of action) Of course the biggest thing going against the Habu for me is that I still get some noticeable negative acceleration/skipping when swiping at high speeds with the Habu, although I never really achieve such speeds in game as I'm not really a low sensitivity player, but my point is that I think the Copperhead is much better in this regard.
For me it basically goes like this - DeathAdder > Copperhead > Habu > G5 (it gets kind of hazy when considering more mice into the equation such as the MX510/518 and the Daimondback, but price becomes a pretty big factor once you get to this point, and I'll be honost in saying that I haven't had any in depth experience with the Daimondback, only knew one guy who had one and never really got to use it enough to get a good impression) DeathAdder has the best control (most important feature of the mouse), Habu has the best buttons (the two mini buttons under the mouse wheel as well as the changeable side thumb buttons can't really be beat, the only thing that comes close is the MX5xx or the new G5), Copperhead is probably the best ambidextrous/finger only mouse that I've ever used.
Keep in mind that I've only ever been expressing my own opinion based on my own play style as I use my mouse with higher sensitivity settings (takes me less than my 10x12 mouse pad to do a full 360 rotation) and finger control.