I have quoted for parts in both the US and China. What I have seen is that generally, tooling is noncompetive - I got quotes for 22X the cost in the US...!
That said, the advice we got from most of the people we were quoting with was to get the tools made in China, import them to the US and produce the parts locally. We didn't end up doing that but I remember being amazed at the crazy tool quote arbitrage...
Bingo. Tooling in the US is ridiculously expensive. For other applications (tools for plastics, injection molding, thermoforming) there is often a 3-5x difference in price.
Actual processing is much less of a difference, especially at volume. So it makes sense to do tooling in China, production in the US.
That said, the advice we got from most of the people we were quoting with was to get the tools made in China, import them to the US and produce the parts locally. We didn't end up doing that but I remember being amazed at the crazy tool quote arbitrage...