What exactly are they saying when they see the price? Do they think it's just the wood cost or do they not get how many hours go into planning and building something one-of-a-kind?
Break down the quote for them, line by line. Show the cost of materials, then the hours for design, build, and finish. People see a big number and panic. When they see 12 hours of labor at a fair rate plus plywood and hardware, it makes sense. They just don't know what goes into it.