Poisonous Storm Bow of Shelter

Just got it out a chest in the Tombs UW, now its pretty high req, but its max, gold, and has an almost max inherent mod...

Poisonous Storm Bow of Shelter
Piercing Damage 15-28 (req. 12 Marks)
Damage +14% (while Enchanted)
Lengthens Poison Duration 33%
Armor +7 (vs Physical Attacks)

So whats it worth as is? If I add some different mods can I increase it's value much? or is the Req. 12 just killing it...

Cheers

around 20k~