There's an issue on the high end of the employee salary scale, too. Many American company pay executives annual salaries in the tens or hundreds of millions of dollars (plus benefits). That adds directly to the cost of the products they sell...
And it's not just the blue-collar jobs. A mid-level software engineer in Manila would be paid around $20-22K USD a year. In a market like Dallas, that same person would expect $110-140k. The cost of living in Manila is a fraction of what it...
The real problem is that the cost of living across the world is not equal. If it were the seamstress in Vietnam would be asking around about the same wage as a seamstress in the states in which case there would be no cost saving having goods...
There was 7500mAh battery for sale on Aliexpress, but it's no longer available. In theory, it should work. In practice, you would be risking the drone every time you took it up.