This reminds me of an old, probably untrue, story:
A company set up a production line but it keeps breaking down and eventually they call in an expert. He examines everything and marks an 'X' on a pipe saying 'drill a 3mm hole here and it will be fixed. They do and it is.
Two weeks later he sends his bill in for $1000. The company CEO is outraged and demands a cost breakdown. It duly arrives.
Marking pipe with 'X' - $1, Knowing where to put it - $999.
The point being to make the ideal lens you need the best quality glass and it needs to be cut in the best shape. You are not paying for the materials but the engineering which requires a great craftsman or woman.