Another factor in cost is the durability. The armor that was worth about 5,000 had a durability of 14 if I remember correctly while the $30,000 armor had around 40 durability or about 3 times more durability. You can see this in items that your repair. Because Geoff never has enough gold for me to sell my stuff to I let him fully repair my items. After the repair some of my items are worth $5000 more dollars.
I found some gold ring that has absolutly no stats at all and its worth 25,000. So some of the prices are odd. I still have the ring only because the npc's in rivertown never have enough gold to buy my stuff. I always unload the havy items so I am not burdened and then the stuff they can't buy I either pile up outside the shop or give away.
It makes no sense to me why they have these useless itesm that are worth alot if the npc's have little gold to buy them off you. I also find lots of items with neagitive stats, like -6 to speed or -3 to sight. These worthless rings and amulets still sell for arounf $500. Kinda strange. <img src="/ubbthreads/images/graemlins/think.gif" alt="" />