As far as the cases themselves go, we'll likely allow as low as 3, possibly even do singles if people really want (though I doubt they will).
With covers, I'm not sure. I have no idea how the other case/cover sellers do it. That's a whole lot of mess to keep track of. I'll ask shadowfox and see how he manages it. Since it's all he does (sell cases and covers) it may be far less of a hassle for him. We sell and produce a large number of items, and keeping track of the prints and whatnot could prove difficult. May just be an all-or-nothing affair. Not sure...