Makes no difference where the cost difference comes from.
You still have a $10 screw driver or a $1 screw driver.
DUH!
Get it?
You said "union made screwdriver," thus implying specifically that labor was the big reason manufacturing was moving to China. It's not. Don't change your story simply because you were caught not knowing what you were talking about.
Get it?
There is a 7% union participation rate in the private sector. So there is a 93% chance that your hypthetical screwdriver is non-union made. Secondly, labor costs on average bwtween 4 and 10% of the retail price of manufactured goods, so at most your $1.00 screwdriver would be $1.10.