Bottles of this type (clear / machine-made / 20th century) likely will never be rare, at least for a long time. Consider that bottles made prior to 1900 not only were made in far smaller quantities but glass was recycled and reused quite a bit rather than just thrown away.
Things start to get interesting with 20th century bottles if you have the complete label, closure, packaging,etc. which is much, much less common. Use that concept as your guide.