@curtisb Rather than focusing on colors, using a greyscale (usually white and black) puts more emphasis on the silhouette of the outfits and the clothes. Extremely high avant-garde fashion focuses highly on materials, construction, and cuts to differentiate from more basic clothing. The way the clothes drapes and such give an interesting twist on just regular clothing, and colors would detract from that. It's basically too much to take in. Also, to some designers, it is what black represents to them. But that's basically the simple version of the ideology behind it.
@curtisb They are sold to the public but they have very small production runs. They're not quite like Zara or H&M in that they can just mass produce everything. That's what makes them quality as well as design. They are usually produced with a lot of quality control. Production for each piece differs but do not expect them to be cheap!
My friend is a fashiondesigner and she is incredibly busy. If she is not working on her current collection she is looking for interesting patterns and fabric, trying to make her fashion as diverse as possible. Thank you for your incredible insight @lovemilkis ! I feel like I understood something crucial about Fashion :)