For cels I would say that Tokaki, Tatara, and
the other animal gods humanforms are rarer
than Suzaku.  Seen 1 human Suzaku cel (which
I would do just about anything to get) - but
haven't seen any cels of young Tokaki, Tatara
and only seen animalform cel of Seiryuu.  
Don't remember seeing any cels on market
of gods Genbu and Byakko.