Good luck finding them in general. I've got a spare or two if I can find them; I stocked up on Target's clearance, and I could be convinced to part with one for a twenty.
Also - do you want to use it stock or mod it? One of them came apart and I'm told that normally, these are nigh impossible to crack open for upgrades. That's the only one I ever played with, but for modding potential, it's hard to beat. If you want that one, I'm gonna take a few more good photos before I ship it.
All of 'em, even the open one, come with retail packaging.