I'm actually concerned about the killing of weasels for brushes, too (yes, according to my research they DO have to kill them). It's sort of an ethical gray area... I'm no vegan, but then again I feel that it's pointless to kill wild animals when there may be other options.
I've never been able to afford real sable brushes, anyway, but when I was considering investing in some I did a little research and now I feel kind of leery of it.
In case anybody's curious, this is the animal that the finest brushes are made from:
http://www.inferret.ru/page-id-76.html
I'm certainly not going to go around saying people who DO use real kolisnky sable brushes are evil, though!
(Just a thought, what if this animal was listed as endangered? Would people view kolinsky brushes the way they view snow leopard fur coats? )
On the other hand, though... producing synthetic brushes may well require the use of chemicals, petroleum products, etc., which could arguably be just as bad for the environment as killing of a few thousand Kolinskies.
Heck, our dependance on the Kolinsky for its hair may save it as a species because it's a useful animal that we're motivated to keep around!
Quite a conundrum, indeed.