A 153-page research titled Valuation Techniques for Commercial Aircraft Program Design by Jacob Markish at MIT breaks down the valuation of the design, manufacture, pricing, etc., of commercial aircraft.
The non-recurring (development) cost of a wing is broken down into engineering, manufacture engineering, tool design, tool fabrication, and support.
For the wing (and the other parts), it's a dollar value per pound of operating empty weight (OEW).
The engineering of a wing (clean slate) costs \$7,093 per pound. The total for the wing is $17,731 (per pound).
If it is not a clean slate design, say the DC-10 / MD-11 example, then it's only 20% of the engineering cost.
The heaviest (OEW) MD-11 weighs 291,120 lb. Given that those dollar values are from the year 2000, then \$7,093 would have been \$4,679 in 1987. For a total of \$1.4 billion to engineer. And a total development cost of \$3.4 billion—near the figure I got to based on projected sales—if MDC would have decided on a brand new wing.
Based on this method, the value is $1.43 billion (1996) to redesign the MD-90 wing.
Seeing how the table below shows how expensive the empennage and systems are, and with the major changes done to those areas on the MD-11, one can see why they went this way.
