We all do it. We judge a fabric by it's price at face value. Often, within a fraction of a second, we decide that it's too cheap, too expensive or just right. All the time we are evaluating. This is human nature and when we spend our hard earned dollars, we don't want to regret it later.
Here in Canada we are "metric" but many vendors still sell in yards and inches. Also people shop cross border all the time. In the U.S. all fabrics are measured in yards and inches. It's a worthwhile exercise to make proper comparisons to know what you are purchasing. In other words, it helps to "do the math".