I have one for ya.. It was cheaper, and quicker, for the furniture manufacturer to ship Canadian lumber to China and have it assembled there and shipped back here.
I have no problem with the quality either but knowing what I know about international transportation and fees, duties etc.. I find it difficult to believe that there is not a place in the US that can be competitive at their volume.
Friends at US Gypsum once told me that costs also include settlements of lawsuits as well as availability of the mineral. Although 2/3 of US consumption is domestic sources out west as well as in Iowa and Ohio, other sources include Canada, Mexico, Spain and China.
In addition to wallboard, gypsum is also used as a soil amendment and concrete additive. The James Hardie Company (manufacturers of Hardieplank siding) owns one of the largest gypsum mines in Idaho. It’s not likely they would sell the raw mineral to competitors for a low price.