Shpaget:
3D printing is pretty expensive for mass production and for the price of a good printer you could cover a good fraction the cost of the mold for injection molding. After that the actual cases are pennies a piece.
True, but in order to get to the mold stage one needs to make a final prototype. I've checked and this can be expensive. For the cost of getting someone to do it I can almost buy my own printer. Once I have a good prototype I can have a mold made for production runs.