No they are not extinct, they actually are a farely new breed from 1949. Like Vidaloco said your best bet is to get them from Russia, since that is where they originate. They are a really cool breed that is similar to the thoroughbred. I have looked at some horse sites like horsetopia and they don't even offer it as a breed.
The rider casts her heart over the fence, the horse jumps in pursuit of it.