as we have improved other buildings, how about an improved trade office/estate agent where we can buy and sell multi level buildings, for example selling a level 3 building you must have a level 1 building AND the resources to upgrade it to level 3, then put item up for sale, then when the purchaser buys the item andplaces it on their island it takes the combined weight of a lvl 1+2+3 timer to build.
the improved trade office could be a mirror of the normal trade office but with grey roofing instead of the usual green ones. in this way not only would it benefit players both old and new as well as reduce the requests in guilds for the resources needed to upgrade the buildings once bought.