Paying $~90/mo for the cheapest iPhone plan that included tethering was an awful deal, but I don't think that AT&T had introduced the $15 off thing at the time. The family plan cut on top of that seems to makt AT&T's prices actually competitive.
Airvoice, an AT&T MVNO, will sell you two plans with 3GB each for $120 or 2 plans with 1GB each for $80.
Airvoice, an AT&T MVNO, will sell you two plans with 3GB each for $120 or 2 plans with 1GB each for $80.