The Silver Wyrae+Kioka is overpay for the black Ezahni, so that's a good thing for your end of the deal.
However, it depends on if you want another Wyrae. You could always bean it/dye it another color, but then again, if you were looking for more pure, then maybe it would be to your benifit to just keep trying to sell the Ezahni for pure.
If you want another Wyrae and Kioka I say go for it. If anything the offer you have for your Ezahni, when added tu wise, is overpay and would be a good deal for you. But if you wanted more pure than anything I would search for another deal.