U.S. Manufacturing costs are almost as low as China’s
Shenzhen China factory owner here.The costs are definitely rising in China for English speaking technical labor such as the engineers we need. We compete with companies like Apple and all the other foreign companies rushing to China these days to keep them employed. But we are still talking much lower salaries overall, for example,  $30,000 USD/year for a degreed Sr. Electrical design engineer with 20 years experience.Regarding rents, the Shenzhen central business section rents are expensive now and cost/sqft comparable to anywhere else. However, good industrial space is still far cheaper, for example, I just leased an additional 12,000 sqft high quality assembly space with low ESD floors in a technical park along with 8 dorm rooms to sleep up to 32 people (4 per room - last owner had 8 per room).   Lease on this new space cost me $3500 per month. There is also a kitchen ran by the tech park where they serve 3 hot buffet style meals per day for $2/day/worker.  I'm not aware of anyplace in USA where you can lease a space like this for $0.29 per square foot nor get a buffet meal for $0.66 cents nor have door rooms for workers.  Now, it is competitive to find this space and you need to lease when you find it not wait 1 day, it took us 4 months searching and we lost several spaces waiting 1-2 days, but it exists.But ultimately what is far cheaper here in China and the main reason I must remain here to make money is for the lower cost of the materials required to actually build the products.There is a critical mass of suppliers here where you can find half dozen capable suppliers for nearly anything you'd need to buy.  For example we do a lot of custom molded plastic parts and many times I can make multiple cavity hard (300K shot life) injection mold tools for plastics for $3K-$5K USD and it would cost 5x or even 10x as much to buy them in USA.  No less, bolts, nuts, screws, electronics all vastly cheaper here.Lastly, as someone else noted, the cost of shipping is much cheaper when you originate your shipping quotes from a Chinese account, especially for air shipping to USA, rates originating from my China company's Fedex account is routinely 50% cheaper than what Fedex quotes in the USA. This really adds up when you need to ship stuff around the world quickly.