Niche. I now a few local women who do pretty well at knitting. One sweater a few thousand. Who do they find who would pay thousands of dollars for a sweater? I'm not doubting you, I'd really like to know, because I knit.
Find a boutique type store that sells hand-knit. That would be in cities, resort-type areas. The woman I mentioned -- she hand cards, spins and looms the wool. Not just any wool either. She's also a got a gift for pattern and color. Her stuff look's top-shelf, stylish, rich. I can't recollect if she's the one who only uses natural dyes. There's a sort of guild of weavers locally -- I've happened to talk to them once or twice when they meet in a hall I have some other meeting at. They take the stuff very seriously although not as anal about it as the re-enactors. The weavers have a good humor and willingness to talk at the level of their listener.
I've been remembering lately a high-school varsity letter type sweater my grandmother knit for me years ago. A great sweater and full of her love, and it fit and was nifty looking too. Wish I still had it.