This is ethical because no one is forcing the consumers to buy the products. Instead, they are freely choosing to buy at the price that is offerred. When consumers buy a good at a given price, they are saying that the good is worth that much to them. If the good is worth that much too them, it is ethical for the producer to charge that much. In fact, you could argue that it would be unethical for the consumer to pay less. If I get $100 worth of value from a product, why is it ethical for me to pay $30 for it just because that is what it cost the producer to make it?
Since consumers in a market economy have choices about what to buy, it is ethical to charge them based on value. It would not be ethical to charge prices based on value for things like life-saving drugs. But when we are talking about things like bottled water and running shoes, it is ethical because consumers have a choice.