While i agree that prices have been stagnant, its also a game of companies wanting to reduce risk. You have unicorn examples like Baldurs Gate 3 which took its time to develop a game, and has stated they dont plan on making paid expansion content, meaning where they at they see the game as profitable, despite spending 5 years in development for it.
Part of the reason why some games have balooned cost is because of improper spending of the money. Many spend a lot of money on marketing which tends to have an overly inflated cost on its own, due to the fact that people have a preference to play whats familliar, however its been shown that also actually making a good game with little marketing also works, and a lot of dev studios havent gotten to that point yet.