There are product categories for which a dramatic price difference does not necessarily indicate a dramatic difference in quality. Shoes, for instance. Or possibly makeup.
Cookware is not one of those categories.
When you're talking about cookware attributes, you're basically looking at three things. The first two are about science:
Reactivity. This is whether a pot or pan will react chemically with the food you're cooking in it, causing an undesirable change in color or taste. Nonreactive materials include ceramics and stainless steel. Reactive materials include aluminum, copper, steel and iron. Not even the most expensive brands can change the reactive properties of a metal.
Heat Conduction. This is how well a pot transfers heat from the burner beneath it to the food inside it. Copper is an excellent conductor -- when cooking with a copper pan, adjusting the burner temperature causes a quick resulting change in the pan. Aluminum and stainless steel also conduct quite well. Again, this is a function of the type of metal used in the pan; it can't be changed no matter how much money you put into it. The other big factor in conductivity is the placement of the pan's heating elements.
It's how a cookware line addresses these issues that, in large part, determines its price …