Need a PC on an almost perfect Shadow Bow

Yeah, I havn't the foggiest clue how much this is going to worth, and that's why I was wondering if you'd be able to give me an idea

It's a Sundering Shadow Bow of Fortitude
15-28 (req 10)
15^50
20/19 Armour Penetration
+30 HP

Thanks a bunch in advance.

15-20k...hard sell, though...