Truthfully Tom? I've had a few items. Not sure if I've ever paid over 20 gold for them. I -think- I once paid 50, but only because I planned on the item to be a gift for someone else. Honestly though, they're too much work to bother with.
I have my priests trying to convince advies to sell the items to the Church, but mainly because we see them as either potential relics or possibly magical items that can be a danger to humanity and must be kept secure.