"The rule of thumb for anyone building hardware is that a product will sell for three to four times that of material costs, Cyril Ebersweiler, the founder of the hardware accelerator HXLR8R told me. “That would be at least a $100 product if you were only selling the Pi,” he said."3x to 4x material costs? Is that retail? What about selling at just above cost and charge these rates for the software?