Just a suggestion I thought I'd put towards the devs, we should be able to enter into a preview mode where we can place down items and preview how things will look. At the end of it the system should tally what you've put down and either give you the material cost of the items needed (taking into account what furnishings you already have crafted in your inventory) or the crown store cost and enable you to craft/buy what you're missing then and there.