stallzer - Those 2
ebay links are obviously not real since LBJ was dead when those covers were printed.
sfriedman's sigs could possibly be authentic - I also noticed that the signatures have variations, which means they are probably not copies (doesn't mean that someone elses didn't do them)
He will need to send them for certification..This costs 50 dollars for them to look (around that) and then I think another 25 or 50 if it turns out it's real and they need to certify it and number it
The 2 certified LBJ autographs I see under completed listings on
ebay went for over $400 each.. Covers like these would probably end up in the same price range.... The philatelic connection is meaningless for the base value (except to the rare person that specializes in autographed covers).
Its worth the money to get it certified.