PC on Req 9 15^50 Dead Bow

i just got this dead bow recently
Cold Damage
15^50
Marksmanship +1 (19% chance whisle using skills)

If i changed to mods so they were better how much will it be worth and if so can you tell me the best mods possible thanks

J.W.

2-4k, don't mod if you intend to sell.