There are two “no GMO” markets: the one you mentioned, and a much smaller market of people who object to GMO for pesticide resistance instead of GMO for disease resistance.

I don’t avoid GMO foods, but I do think our current scheme incentivizes finding the strongest poison and correcting the plant to resist it, without concern for how that poison affects the rest of the environment. I would much rather we engineer the plant to resist the disease directly, but it’s harder to double dip on profits (RoundUp and RoundUp Ready) in that scheme.