PC onStorm Bow

I found:

Storm bow of fortitude
15-28 (req 13 marksmanship)
Damage +15%^50
Health +29

The 15^50 IS NOT INSCRIPTABLE! - It's stuck if you can say so.

I know the reqs are high, but is it any good?

And, how much would it be worth if it was req 9?

10k.... im geussing

5-10k shame about the req