As counterpoint I have a pair of Wharfdale W100's that I bought new in 1969. I used them until the mid -1980's but then left them stored. Now they're small tables in one of my workshps here (they are large doublewide floor standers with sand filled walnut cabinets weighing 100 lbs. each.
A couple of years ago I thought to try them for a downstairs shop system and found neither tweeter playing and the overall sound muddy and bass heavy to my taste. I did invest in a pair of decent tweeters and a few capacitors and got them playing but don't much like their sound. They never were very detailed playing speakers and they'd likely be thought slow in todays vernacular, probably designed for those who enjoyed a large symphonic sound. Admittedly when I bought them classical music was my main love; now I have a much broader musical interest.
I'm saying all of this to say that an old speaker may be one made for a different musical environment. Although you might say something like "music is music - as long as a speaker can reproduce it accurately then all is good" I've come to not believe that.
Technological developments have brought speaker engineering to a point that a particular speaker for a particular type of sound or music is very much a reality. While it complicates choices tremendously it does enable us to find speakers which can be tailored to our ears and our musical tastes.
So the danger in shopping for deals in vintage/used components may lie in the possibility that even something once thought to be state of the art may not be so enjoyable in comparison to newer designs.
I have a pair of Klipsch Heresy's here that I bought three years ago. They stand mostly mute, as testimony to what I've just said while I prefer the sound of a little pair of NHT Super 2.1's coupled with a JBL 10in. sub and a Marantz networked receiver.
If you chose to ignore what I've said then at least look for used JBL speakers. The ES line are underappreciated, IMO, and thus make for good deals.