My guess is that will happen some time before 2030, if western society as we know it continues to exist in a recognizable form for that long. 
Wages will be roughly the same by then, won't they? 
And wine cave warriors will concern troll the poor about their "bad choices" and look down on the demographic's health problems because they can't afford Whole Foods treats and have to lean on instant ramen and other food desert staples.
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I suppose i should have given a small caveat - i live close to mexico. Produce is cheap here. I can go to a fruit stand and buy avocados for 75 cents each. Bananas by the lb are about .38 cents. Citrus, pineapple, coconut, chilis, peppers, onion, garlic, melons, and a few other things are cheaper here than the rest of the US.
Honestly i always assumed it was proximity to mexico.