If you compare Internet, discount prices to niche, yes, they are more expensive. (But then, the discounters might be selling outdated fragrances.)
If you compare department store prices to niche, usually they're in the same category. I paid $80 for Chanel No. 19 and $90 for Parfums de Rosine. No big difference. You usually cannot find the niches frags at 50% discount online like you can the department store brands. Some niches houses like Creed and Montale are closer to $200 for the big bottle, but then, if you like the fragrance that much more, it is worth it IMO.