I've got some insider info! I work at best buy, so I know how many most of the stores in my district are getting. My store is getting 36 of both colors, and the other smaller store in town is getting 12 of each. The rest of my district stores are getting anywhere from 15 to 20 of each. The ad minimum is probably 12.
I suppose that is fairly small. But I'm not sure if they will be huge day one sellers, I haven't received any questions about it, and people are surprised when I mention it coming out in a week. If they do sell out I would assume the black to sell out quicker, because I'm assuming that only core gamers know about it, and that the majority of core gamers would prefer black to the blue.
That said, I am going to preorder one at a gamestop as soon as I can (as best buy, being fair, will not hold one for me). I used to work at a gamestop, but have lost all my contacts so I don't know what that front looks like. Bosshog (MNCDover, love the comic!) might still work at gamestop? I'm sure at least one of us does, and whoever works in any sort of retail should speak up and let us know what its looking like!