Then surely the simple answer is don’t buy them?
I would guess that the developer is free to charge whatever they like… Much like any other product in any shop in whichever country you may be in, if the item in question seems reasonably priced to an individual, then they’ll buy it - if not, they’ll either pass on purchasing the product, or wait until it’s on sale at a future date. Nobody is forcing anybody to purchase anything, value (like art) is entirely subjective and will change from person to person.