The frontier between ''vintage'' and ''junk'' ?

I would modify that last phrase to: 90% of what is sold as new "will become junk soon enough, the other 10% will go on to become Classics"
Much better 'phrasology'
And since it will all still be sold long after it has stopped being manufactured.. the earlier phrase will ALSO apply:"of 100% of stuff sold" 90% of what is sold as vintage is junk. Perfect see?

We have a Winner! Junk that has become treasure.
The ad for a pair of XXXXXX speakers. 1968 famous.. look closely, chips, damaged.. Hmmm a little rough for the asking price of ONLY $120,000.00
Yes $120,000.00 NOT a misprint. Speakers the dude probably found at a rummage for $100. are being suddenly transformd from "junk" to "Treasured antique". I do not want to get into trouble here for 'dissing' someones ad so just say you gotta search for it. but not many have a price tag like this one.

I always find great deals at thrift stores, usually people get rid of his vintage stuff to buy modern hifi. They didnt know the treasure they got in their hands.

The word, which is largely a derivative from the world of wine, is overused simply in the name of salesmanship. In terms of how to define it, that is nebulous. That being said, I did snag a pair of speakers off of Craigslist that I would qualify as vintage: large Advents circa 1975.