The main reason for such cost is the quality of these furniture items.  As they are not meant to be changed the year, they should be made in a way to protect the utilities, important documents, clothing items or dishes. Also, they must not fall apart when encountering food or water. It means a lot of time and effort goes into producing these cabinets.  Estimated it takes about 6 hours to build one standard size piece. With that much effort and resources invested; these items are expensive to buy.