I do wonder though... How much cheaper is it really? What if the externalized costs were factored in?

Currently all manner of costs are put onto the environment rather than the producer or consumer: Soil erosion, soil degradation, fertilizer and pesticide runoff, biodiversity losses, greenhouse gas emissions, etc... All of which are huge issues, which we can't keep ignoring like we are.

And even after ignoring all that), most of 'the West' still needs to heavily subsidize farmers to make them competitive with imported crops.