I guess it all depends on who you ask this question to really. I've seen big fights break out other places over this issue, so it's refreshing to see such a high level of civility and tolerance here in this discussion so far. I agree with most of the comments made in this thread too. I think just using some common sense on what seems fair to take off the pegs works best. Consider the other collector's needs in your area, and how new and/or abundant a particular army building figure is, before deciding how many you'll be buying on any given trip.
I also agree that this shouldn't even be an issue in the first place, if Hasbro just played it's cards right, and made enough army builders to satiate demand. There's so much money to be made with these types of figures, yet no matter what, it seems that there's never nearly enough to fill the demand, and that's just not good business sense if you ask me. Top army builders should get shipped in solid cases for a while, so the army builders to buy to their heart's content, and all the rest of the collectors and kids can buy the one or two that they want also. No reason that shouldn't be a manageable strategy.
I'd also strongly suggest not using army building figures as limited exclusives, like the Target Clone, because that's just always going to lead to problems. Hasbro should just go back to putting out those white mailer boxes with 4 figures in each one, and everything would be fine. Why is that so hard to do now?