The price of design
That leaves the prices of designer clothing. Do not worry; this is not going to be an essay to justify everything. I do think the mark up on clothing (and accessories) is sometimes too steep. I do not see the added value of having a brand name upon a regular shirt, so I would never buy it.
However, we live in a world were branding seems more important than craftsmanship. Where a logo is more worth than a beautiful hand stitch. Where people no longer seem to understand the time and effort that can go into fashion design. We mostly want our clothing real cheap; I lost count of the amount of H&M's in Amsterdam. If it is expensive it should be a known high-end fashion label and the logo has to be visible somewhere either for the insiders (like Margiela) or for everyone to see (like Dolce&Gabbana).
Independent designers, no matter how driven and talented they are, will struggle with this. While time and money is spend on concepts, samples, fabrics, yarns, more samples, more fabrics, and more yarn the costs of the final pieces will raise. A collection is not suddenly there. The investment made is ideally calculated into the price of each item. Additionally, there should be some profit to allow a next collection and to provide a salary for the designer.
We have got so used to low prices for clothing it almost seems normal, while it should not be ordinary. If you pay 10 euro's for a shirt in a shop you should realize there is someone (and maybe more than one person) not gaining any profit from it. And it won't be the shop you bought it in. While I understand it is tempting, and of course I have bought cheap items as well, I decided to not be part of such a company.
I searched wholesaler's who sell fabrics and yarns produced under proper circumstances. I value craftsmanship and slow fashion and therefore my work is more expensive but also more valuable. There are more designers, more labels and more stores following this approach. Do not judge them on their price. Judge them on their products and their quality.