You are right if you plan to double the costs of any component you mount on this board or you can chose to buy 25pz at 12$ (Digikey) and sell the board for 40$ (+8$ respect the cost of 1 RFM95?)... without considering that the money remains in the US with Microchip
This thread is diverging off topic, but let's wrap this up.
One Q first: did you ever try to create a product to sell, and make a living from it?
Anyway I am all ears about your proposal of making an economically viable product, what the price should be.
For making this for commercial use - depending on many factors like how complex and time consuming it is to make something electronic - very roughly you have to double or more like triple the cost of BOM. From the "profit" margin you have to cover a lot of other costs (like failed boards that go in the trash) and taxes, and remain profitable to pay your own personal bills, feed your family, and save for retirement
For you as a hobbyist of course you only count the actual cost of the parts without the worry of having to deal with any other risks or costs.