It's tough to put a price on things, like the article said, R&D isn't included in the cost of a part, and yet the part can't be built without the R&D. On top of that, it's not clear if the article is talking about material to build the parts. A lot of teams make their own carbon fibre, so the cost would include the amortization of the machine, but that might be part of the capital budget which is outside of the cap. I would expect, like most things, the most expensive part is paying people to do the work. I'd guess most of it is done either by hand, or someone programming a sophisticated mechanical system.
Then you've got to store and ship the part. I understand part of Williams' pain is their logistics system is out of date, so the amount of time (and time = money) to retrieve a 50 cent washer is 10 times longer than Red Bull to retrieve the same part, making the inexpensive parts 10 times more expensive for Williams, which I'm sure adds up over building a single car, much less rebuilding entire cars a half dozen times.
I get why the sport likes to use common parts, they can probably be created in batches through cost effective methods.