myself i always recommend that you try to find a somewhat local company that you can work with...it is my opinion that one of the main things that separates the great
sign companies from the rest is the ability to troubleshoot and it is not necessarily harder to solve the various issues that arise with a non local vendor..it simply takes more time (shipping, time zone differences, etc).
but as far as shipping goes. if you are pricing your product correctly there should be plenty of profit. i have the skillset to manufacture my own cabinets. the last illuminated project that i did was shipped from the west coast to alabama and for the price that the manufacturing company charged (including shipping) it was a no brainer (the final invoice was roughly 15% more than my cost of materials would have been if i was to manufacture them myself).
i would get prices from a couple vendors and see where the cards fall. an alternative would be to have them make you a kit and you assemble the precut pieces and buy the face(s) locally versus shipping a large fully assembled
sign if shipping is outrageously expensive.