"Appropriate" is questionable. I already explained above. What is "appropriate" for raising a price? Or what can be called fair pricing? I don't consider raising the price fair, when the merchant has no difference in expenses. It's called a rip off. It is not irrelevant and as I said, it usually happens only when competition is weak. Healthy market tends to prevent such bad behavior, because completion could successfully use the lower price for both cases and all customers would prefer them.