in ultima online the way of trading large sums of a given item (ie 500 charcoal) as well as a variety of crafted house add ons and such was to get a blank deed and click the item into the deed, thus making it a "deed for 500 charcoal" or a "deed for a pentagram" etc that could then be placed or redeemed inside a bank or container.
this would allow for a more expanded traders market as you could then sell chests, tools stations, braziers, even buildings and other constructed objects either via vendor stands or barrel swapping like anything else. i would stay away from adding inventory items (such as the charcoal example) as it would eliminate much risk in trading large sums of stuff. however i think this would be a good addition to facilitate the buying and selling of constructed items/structures