It's prebuilt and handmade, hence the price. Making it cheaper - molds and better plastic in them would never pay for itself. It's a large model so either a huge injection molder, or one wall at a time. Add to it the fact that probably between 30 - 50k needs to be spent per mold (one for a single wall) Add in time for the dude to supervise the machine. Etc etc. Shit would add up. For this, an artist probably makes them, assembles them en masse, could probably use low volume techniques. It'll be more expensive, but you can put 2 - 3 in each shop, not many people would buy them anyway and it gets free marketing (as we can see in this post). Depending on the time it takes to make one, the dude could easily be making $50 an hour doing that.