One choice is to make use of the plentiful local produce markets.

The problem there is that the best produce gets exported. I've seen garlic from China in supermarkets for example.

Ah yes... the infamous garlic from China in my local supermarket.

https://www.google.ca/search?q=chinese+garlic

Personally, I avoid it.

The google link you provided returns a snopes article about garlic roots, a blog post from McGill saying theres no problems with using human feces as fertilizer, and a bunch of natural/health food sites claiming Chinese garlic is filled with toxic chemicals. Is there any reputable source that says Chinese garlic is bad?

Why do you need a reputable source for that? Why not just taste it? That enough of reason to avoid chinese garlic.

Had no clue this was "a thing". I didn't buy it because "I can't believe we're importing garlic bla bla bla...".