pc on Gemstone Axe.

I have this Gemstone Axe I bought unid at imperial sanctum for like 2k.

I I.D.'d it and it turned out to be 15^50 but with a req of 12. So I went ahead and added the zealous axe haft along with a +29 hp grip that I had laying in my bank. I went ahead and added them, assuming that even though its a req 12 somone may want it. The only problem is, I have no idea what an asking price should be. anyone help me out?