Geez, maybe flying is always that dirt cheap in Ohio, but it certainly isn't near that in most of Texas.
C-150s at my flight school were $45-50/hr, C-152s (what I used) went for $55-65, and C-172s were $70-80. Things are even more expensive in the Houston area.
And $15/hr instructors?? I have never seen one for under $30, and most are $35-40/hr.
Most of my PPL training was in a $55/hr C-152 with a $30/hr instructor, so my total cost was somewhere around $4000. This is probably below the national average.