There have been a few good HN threads on the topic previously. Here are a couple I had bookmarked:
I might not be able to get whatever pair I want right now, but I'd find a decent one. The quality from a fashion perspective would be miles ahead, I don't even care about brand name; just how they look. Sunglasses for me are something that I actively wear 1-5 pairs of at a time.
Frankly I could afford to pay $100-300, but don't need to. Most people care more about the brand and status aspect, but I don't, just how they look. $50-150 for something like a pair of shoes is a reality most people can and do deal with. If they (Zenni) looked like glasses I'd want to wear, I'd jump at them. American optical have aviators in that price range, and aren't owned by luxottica
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I bet what often happens instead is that the higher margin company just buys out the cheaper guy, and... it's back to the higher prices!
Nintendo did the same thing, minus the buyout, in the eighties when video game manufacturers tried to subvert Nintendo's control in that market.
You don't need a full fledged monopoly to upset market forces. Even the existence of a single large entity that can make unified decisions destroy a healthy market