Actually, I think Anime Museum is the only place
that I have seen sell RahXephon douga/genga.  I
have seen settei (copied and original) on
Mandrake's Auctions and copied settei on YJ, but
might have missed any douga/genga on those two
sites because it seems to be a rare occurrence.  I
don't think I have seen anywhere else get any for
sale..