To address one of your points, just because the crop is inside a greenhouse (or even indoors!) does not mean you won't get pests. Anyone who has had fungus gnats or spider mites even in their far-spaced house plants can attest it happens :(
Yes, but as loewenskind pointed out. It is exactly like quarantine. think about it this way if we can keep entire football fields dust free for years at a time to fabricate micro-processors then surely we can do this?
Something that really amazes me is that technology has been pushed to limits that we can't imagine. Who would have thought that we are now engineering things 100 atoms apart? Unbelievable.
Well, once you go indoors you have a lot more control over this. Think quarantine scenario since this is basically what we're talking about. Nothing gets in that hasn't been cleared.
When you're talking about what you put into your body, which is directly related to the quality of life you're going to have (you may not see the effects of this right away but you will see it), then I don't think cheap should be our first concern.
Having said that, it wouldn't have to be insanely expensive either. It depends on the scale, right?
