I think there's value in both what JL and Tony V are saying.
It's true that prices are ultimately what buyers and sellers agree to. Basic economics. The time, materials, overhead, etc. that went into an item don't determine what the selling price will be in practice.
But the exercise of calculating those costs is useful, because it tells you what your break-even point is. If you don't know what it costs you to make something, you're not going to be in business very long.
It's also good to remember that "value" or "worth" are subjective ideas. The fancy brand name might not be "worth" the premium price to me or you, but it is to some, which is fine for them (as long as they can really afford it.) The difference is that some people place "value" on things like brand names, rarity, or celebrity. Others don't. Different strokes is all it is.
Ultimately we have to be able to communicate the value of what we sell - both actual, functional value and perceived value. And we need to focus on those who match and appreciate that value.