According to research conducted by NPD DisplaySearch, the Sapphire screen inside the Apple Watch costs only $27 to make. One of the displays is 42mm in height (1.50-inch), while the 1.3-inch display is 38mm in height. Both are said to sport the same screen resolution - 240 x 320. If my math hasn't gone weak, that's roughly 260ppi and 300ppi pixel densities for the larger and smaller displays respectively.

The estimated cost of the 1.50-inch display is $27.41, out of which $19.55 is for the sapphire-covered touch panel. The remainder $7.86 is of the display module.