Hard to say. The bottom 98% Scorns are falling drasticly in value every day, allmost. I remember I found a Skorn like yours the first day of 1.0.4 and solt it for 90 mio. Now it's close to worthless. It's really hard to say how much it is worth (check with the lowest comparable one on Ah and. If it has been out for a long time, you have to price yours 1 mio or 2 below it), but I have a suggestion:
Sell without buy-out with a start price around 2 mio. You'll get what the item is worth.
I searched Ah, and yours were the lowest with a but out. Though, another, better one, was out without buyout for 20 mio - with no bids. You aren't the only one overpricing; of all the skorns with 450+ strenght, there were no bids on any of them. That means its value is hard to estimate. I wrote 2 mio above, but I think you should aim a bit higher, even though I don't think it's worth much more personally.
But. Sell it fast before its value vanishes completely. I'd just put it on AH to 5 mio without buyout. You can try 9-13 mio as well. There's always people dumb enough to pay waaaay more for an item than its worth (compared to other items - since I'm of the opinion "things" is worh exactly what you can sell it for on the market).