The first thing I have to do is implement the idea and prove that it also works in reality.
Then I have to design a circuit diagram and a circuit board layout.
Now prototypes can be made which have also to be tested by volunteers of yours.
Afterwards, if you are sure that everything works, you can ask the manufacturer for more pieces and determine the price.
The price for the module will be cheaper than the one I already have, because the display would be omitted.