Joe, if B&N does not have Labyrinth Lord (basically a clone of the Moldvay / Cook / Marsh Basic and Expert sets) in stock, then you can have it special-ordered.
I have been pretty impressed by the turnout for RPGA 4E relative to Magic events at the FLGS. In both, I see a wide range of ages -- but that for 4E (from elementary schoolers to half-centenarians) is notably broader.
Still, the table-top gaming scene (from what I'm able to see of it, which may not be representative) seems to skew older than it once did.
There seems to be a similar shift in the (American, anyhow) comic-book business. A lot of "geek culture" seems to me to have become even more geeky, probably chasing a narrower target demographic with more per capita to spend on it.
Adjusted for inflation, the 4E books seem about as big-ticket for a kid as the 1E volumes were in their day. Many games' rulebooks (usually saddle stapled, although 2nd ed. RuneQuest was perfect bound) were offered separately as well as in boxed sets.
My impression is that pre-teens are as avid readers as ever. The really bookish were in the minority, I think, even before television. There seems to be a special appeal in books for those who have not yet mastered the "magic" of literacy. When first that door is opened, the novelty of access to such a treasure trove tends to be intoxicating. If that's not exactly timeless, I think it has at least a few generations left! Look at how much of the Internet is textual.
I am not well versed in it, but I gather that rather free-form narrative games played online have become quite popular with the younger set. That reminds me of some games my friends and I had cobbled together and were playing at the time we first encountered D&D.
It may be less common now for kids of that age and socioeconomic class just to wander over to Buddy's house and get into some game played with paper, pencil and dice (or any of other myriad ways we found to entertain ourselves).
So, there may well be a whole new set of "grass roots" sprouting quite outside our loop. I am inclined to think that if there is, then common ground is more likely to be found in rules-lighter games akin the seminal works of our hobby than in the latest manifestations of decadence.
On the other hand, the trend away from old-style roleplaying toward a "storytelling" mode may provide more points of contact. It is not what "D&D" means to me, and I find WotC's design conflicted and cumbersome, but it seems a more sensible course than trying to ape video games.
Those, I think, answer better the needs of a demographic that in former decades played D&D simply because it was the next best thing -- what was available when the World of Warcraft program seemed even more far out than a manned mission to Mars.