While not entirely germaine to this discussion of quantity limits, exporting iPhones, presumed innocence, and iElectricity I hadn't seen this part mentioned yet.
There is only one reason to skip most of the apple stores near or around Newton, MA. It's to avoid the Massachusetts sales tax, as New Hampshire has no sales tax. She was reportedly carrying $16k in cash so without paying sales tax, she would be able to purchases potentially 2-4 additional iPhones.
I think she knows a bit more English and "how things work" than her story would otherwise have us believe.