You are right in that what these scalpers are doing is completely 100% legit.
That does not mean that it is ethical. Sure, I could wait another 2-3 weeks for new stock to come in, or order online. The world isn't going to stop spinning on its axis simply because I don't have my shiny new ipad. However, the issue is that I shouldn't have to.
The whole point of Apple introducing all these new purchasing options/restrictions is exactly so that as many people who honestly want to buy an ipad for their own personal consumption is able to get one quickly and readily through legitimate channels, not for opportunists to spin them off for a quick buck.
For common folk not willing to pay that extra premium, you tell me, is it fair that they have to wait that much longer thanks to some person in front who cleared out all of the store's existing stock, and not because he has 20 family members each wanting their own ipad? How would you feel in such a situation?