Estimating Assembly Cost
Won't fit in a comment field, so:

Note that you say "assembled in the US" - but this would apply only if expressly stipulated, as many companies with a US front end use Asian assembly or Indian or ... .  I can recommend a well priced and highly competent and conscientious assembler in Serbia and can suggest a SD, CA company who assembles in all of USA, mainland China and Taiwan. 



Very much comment only:

US: $More than China to $Much more than China.
 Use following as a very rough guide only.

China: 

Reasonable rule of thumb is 1/3 cent US ($US0.00333 cents US) per pad or termination for SMD. Through hole fits inside that cost as long as percent through hole termination points is small compared to SMD termination points.   

The above "formula" just happens to come out very roughly right in many smaller cases. It is not a true reflection of costs in extreme cases. eg 2 terminal devices such as capacitors and resistors would be costed at 2 x 0.33 cents = 2/3 cents each. An 0805 1% metal film resistor costs somewhere around 0.1 cent in manufacturing volumes so the assembly cost swamps it. Whereas an eg SOIC14 pkg would cost at 14/3 ~= 5 cents and a SOIC8 at 8/3 ~= 3 cents whereas an eg TQFP44 would cost at 44/3 ~= 15 cents. The resistor install cost may be able to be worked on and the TQFP cost, as some aspects of pick and place costings scale approximately linearly with pin count and/or package size and others are very non linear with size.   

When quoted for Taiwanese manufacture via a local NZ middleman who claimed a modest markup % on costs I have had quotes for many times the cost of what can be achieved directly in mainland China.