"Decent sax" and "free" sadly don't go together. In fact, you can still pay quite a bit of money, and fall short of "decent" in the saxophone dept.
Pretty tough instrument to sample/model/fake, I guess.
I'm sure others may know of the hidden gems, sorry for not being helpful, but I've always had a gripe about faux hornage. It's frustrating my entitled sense of immediate gratification. :)
cheers,
-Tom