i wouldn't pay that much for it either, but i do it for a living and i know i wouldn't duplicate it for less than that for oak, and as the wood gets more expensive, so does the built in. there is between 5 and 7k of material alone in that office (double that for something like mahogony) and i worked on it for about a month and a half on my own. to shorten time, i would have to pay one or two people who know what they are doing which would cost me between 3k and 5 k for a 3 week period. additionally i have to pay myself and put some money aside (to pay for insurance, tool repair, workers comp, msc. material not covered in the initial bid, etc.) on top of that. custom costs a ton of cash, especially if you want it done right the first time and i'd have no problem finding someone who would spend 20k for that office.