Value is relative term. And with covers there are many factors that go into determining value. Are you asking what someone might pay you for them? If so then there are very different numbers depending on whether the buyer is a private party who very much wants one or more of these, or if you are going to sell them in an auction such as
ebay (a lower number) or if you are going to sell to a dealer (most dealers would not pay very little or pass on your offer). The majority of these seem to be in the 10 cents to 25 cents range that you find in dealer's "junk boxes" but there are a few that an eager collector might pay from a couple of dollars to more. From what I can see of the flight based ones, the most "valuable" one would have been the 1931 Charlevoix emergency airmail - the first one in your posting but unfortunately it is addressed to A.C. Roe who has a checkered past of creating flight covers "after the fact" i.e. forgeries. Some of his covers are fine, some are forgeries and it is next to impossible to tell the difference. As such it would have been something that some people might have paid as much as $20 for it, but with the Roe address my guess is that you might be lucky to get $10 for it. The other flight related covers are in the 25 cents to $5 range with the 1926 ones being at the higher end in the $3 to $5 range. If someone offers you more then my suggestion is to jump on the offer as these sell everyday on
ebay for these prices when they sell at all.