When it comes to mass production, it's best fit to design the whole board with discrete components rather than buying individual components, assembling and integrating them. It simply adds to the cost as well as space. Under Adafruit's courtesy, I have made a few changes with some components and added some design notes. The OLED module is pretty straight forward apart from the bidirectional logic level shifter. You can find more information about it in the following pdf: http://www.nxp.com/documents/application_note/AN10441.pdf

Refer the following schematic for the same: