[Trivial googling shows you $750K to $1.25 million Euros per hectare](https://www.floraldaily.com/article/9574650/half-fewer-order...). At 400 square meters of greenhouse to feed a single human being (a reasonable estimate, lower bound being 300 under super intensive conditions with experienced growers), that's at least $30K _per person_ under the existing constraints of the industry just for an industry-standard greenhouse. You could of course lower construction costs and do the bare minimum, at the cost of a dramatic decrease in yield.
That of course assumes materials and fabrication is abundantly available and wouldn't see an impossibly high rise in materials and service costs if suddenly the entire world were to demand greenhouse construction with the attending demands in electricity distribution, power generation, and the sudden need to turn most of society into a sort of high-tech agrarian population, something that just doesn't happen in a year.
This took me 5 minutes to Google.