There are reasons why niche are more expensive.
1. They use more expensive higher quality ingredients
2. They take greater risks in creativity than designers, and risks entail high payoff
3. They take pride in exclusivity. People are paying more money to smell different from everyone else.
4. Niche companies may be happy with serving a small base and if they lowered the price, they wouldn't have enough juice to serve everyone.
Whether the higher price is worth it is up to you. Prices aren't universally directed to everyone, but just at the people who are able and willing to pay them.
Think of a niche fragrance like an iphone. The new $500 iphone is great and worth the money if you have the money and want a great phone, but there are still plenty of cheaper smartphones $100-150 that work great and are a perfect terminal choice for anyone.
Personally, I like both designer and niche. To me, both are worth it at their respective price lines.