I feel like what you’re paying for is largely the workmanship.
Then, too, when it comes to materials, we would have to compare the cost. Does resin really cost that much less than wood? Considering the resin must be bought and turned, the cost of the tools to turn it (some resin can’t be turned using the same tools as wood), probably extra R&D to figure out how to work the material and how to make it work as an instrument, etc.?