I suspect that those folks who answer survey questions of "would you pay more for made in the USA" with "yes" are thinking (if they are thinking at all) of paying $2 to $3 more on a $100 item, not paying $110 more on a $100 item.
None of the surveys are ever crafted to ask: "How much more would you pay for a $100 item for 'made in the USA'?".