I found this great Riding Couture site. I love it, but haven't actually ordered anything.
I also found this short video clip re a 2010 show outfit on the Horse and Rider UK YouTube site. There are lots of interesting videos there, i.e. more clothes, plaiting how to's, training, etc.
Another favorite for dressage clothes, this time a blog - Sho Clothes - Dressage Cothes and Accessories
I think I'll have to make a fashion page! Hmm, I'll add to this page and create a tab. Ideas? Suggestions?