Storm Bows are still in high demand but there seems to be too many around at the moment. Still, if my 13^50 (requirement 10) is worth around 50K to a potential in-game buyer, I guess a 14^50 (requirement 8) would fetch around 100-150K. I guess high end items are always worth more to people who really want them. Upgrades don't really matter on bows.
Although perfect health and a sundering 10/10 or vampiric 5/-1 would increase the value somewhat, a ranger who has played around with different bows would generally know the types of upgrades he/she needs.