Only 75% of a product on the market will be sold each day in a particular region. For example if there are 1,000 T-Shirts on the market in Region 1 every day, only 750 of them will be sold per day.
25% of a product will be sold to price-conscious consumers who will buy only the cheapest products.
In the above example, if your product is not the cheapest 250 in that region, it won't get sold.
25% of a product will be sold to quality-conscious consumers who will buy products with the highest quality, and they are willing to pay up to 25% more than the market price.
In the above example, you can charge up to 25% more as long as you're confident that your product has the best quality on the market.
25% of a product will be sold to brand-conscious consumers are brainwashed to buy the most well known brand even if it is 25% more expensive than the market price.
In the above example, if your product is the 2nd most well known brand out there, you may still sell some if the top brand supplies fewer than 250 units on that day.
What to do?
It is not necessary to do any of the above if you're monopoly because 75% of your products will always be sold to someone.
You can also second-guess what your competitors will do if they produce high quality goods or spend a lot in advertising. They are likely to charge higher-than-market-price and you can always corner the 25% cheapskates.
Likewise, if you're competing with cheapskates, you only need to spend a little in training and advertising to have an edge in quality-conscious and brand-conscious consumers.