From my third link: "Exports of avocados from the state of Michoacan, the top source of both the fruit and immigrants to Chicago, have risen fivefold since 2004." And that was in 2008. Mexicans are genuinely starting to be unable to afford avocado. This is decidedly bizarre to me, since it's a common staple food in Mexico. It's like hearing that potatoes are too expensive for the Irish.
I can't find accurate avocado prices worldwide, but the soaring prices over the last decade or so are easily attestable in Mexico, or at least their effects are. I think the prices have always been high in the US due to tariffs and transportation costs. So perhaps the prices haven't changed much, but the demand sure has.