I also see that the shop layouts and resulting limitation of sellable items might be detrimental to gameplay. I'll re-think it. Maybe I should limit not which sections you can buy, but how many of them?
I think once there is a mix of parties from new to experienced then it will work. As it is, the layout I have is not good for new parties (although I can occasionally sell them items, they are generally not of use in the lower level quests those parties can do so my reputation with them suffers).
Maybe allow all shops a 'basic' table or such that allows items that can be bought for 5/10 gold to be sold on?