But if the product you're selling in your store was made using charity? Or gifted you by the government? then high prices couldn't be justified by R&D costs.
True, but remember that you're not just paying for the research cost of Drug_X when you price Drug_X. You're also paying for all the research that failed, that didn't produce a useful drug. If you spend 100 million researching 100 drugs, and one of them produces something you can sell, you don't need to make back 1 million when selling that drug. You need to make back 100 million, plus a profit.
This is patently false. Without regulation, all goods are priced by what the market will bear. It might be true that if successful drug doesn't make enough to cover the cost of failed drugs the company will go out of business but that has nothing to do with pricing.
The problem is that without competition drug companies can keep raising the price as long as enough people will buy it at the new price so that they make more money than all of the people buying it at the old price. That is why really old drugs that have been around for a long time have their prices increase. Not because there was some new research but because the lack of alternatives means they can just do it.
If it’s anything like the CF Foundation that helped Vertex develop Kadelyco, the non-profit saw an absolutely massive return by selling the right to the drug.