Modular manual/ad cost breakdown

Including in the manual/box/ a card 

This module sold at cost or
This module sold at cost +$10 

Then itemized list of materials like 

Custom circuit board - $2 
Audio jacks - .35

Etc 

Or maybe just 

Electronics components 

$7

But i like the breakdown of each component because it really lets people see where the cost is coming from 

Also 

Circuit board design salary
Roughly $2 
Or whatever

Thats harder to actually calculate