The 3D print may just be for prototypes and not for production. (I don’t know.) But even if it is for production, 3D printing isn’t especially cheap if volumes are in that middle range between a few units a week to where true molding becomes economical. 3D printing can add lots of labor cleaning up parts, wasted filament and time when prints fail, etc, not to mention the printers, supplies, and labor involved in printing those parts.
Those 3D prints also took someone’s time to design, draw, test, and redesign. Plus there are all the other costs involved with commercializing something. If you think you can build your own for cheaper and don’t mind the design time, have at it.