Chinese suppliers generally earn low profit margin. My ex-employer, a company owned by Canadian, export from Shenzhen, earned 7% profit by creative accounting to minimise paying tax in China, then they sold upto 100% profit to other US retailers. The final retail price was 300% to 400% of the export price from China.
Chinese owned China factories generally only made around 10-15% proft due to local competition and price pressure from foreign buyers/merchandisers who deal direct with the factories on behalf of the importers.
Therefore if you cut off the middlemen in US, go direct to China to do your own sourcing, the cost saving is huge.