It seems so to me - for the assembly it seems to make no difference if you order 1 or 20, only the component costs multiplies by the number of units of course.
It’s only when you hit their “component limit” that you have to order less than 20 units to stay within that limit to get the cheap assembly price.
And since the flat costs exceed the variable costs by quite a bit for the typical non-expensive components I use, the cost per unit (delivered to my door-step) improves dramatically if I order 20 rather than 5…
(Plus, I’ll need all those parts for my robot army 
)