Cheaper than a slave? A slave that could be forced to work all day long? It is my understanding that the slave plantations grew their own food, and so the monetary cost was effectively non existent.
I am having difficulty grasping how a group of poor peasants living in Turkey or China or India or Ethiopia or Brazil can produce a cheaper product than a slave plantation. (Weren't they using slaves in Brazil at this time?)
Other than shipping costs, I don't see a lot of variability, and that's *IF* shipping costs from Egypt were cheaper.
Meanwhile some guy in China or Turkey lives very frugally, so his costs are less. I think something similar happens with coffee or rubber or tea. The small peasant proprietor could actually produce more cheaply than large scale operations because his costs are less since he needs less to get by.
Now take the value of money into account. If foreign currency is cheap enough and people only need to earn a fraction of the money value that they need to survive in America, they may be able to undercut slave operations in our part of the world. Why do you think countries devalue their currencies? It makes their products more competitive on the world market.
But you really should take this up with the other guy. Two minuses might make a plus and one or the other of you might actually see the light.