Buying used: how old is too old?


Considering buying some used speakers from a well established company, e.g., Wilson, Focal, B&W, etc.

Aside from obvious technology updates, do speakers have a shelf life? If so is this measured in overall life, or number of hours played?

I’ve read some reviews that some speakers can really improve with age, no doubt longevity is going to be influenced by speaker drivers. Perhaps paper breaks down before other materials—I don’t know.

Old flagships can be bought for a fraction of their original cost and less than new mid-level speakers. No break in needed! But maybe they would be broken down?

I’m sure there have been numerous threads on this topic, but I didn’t find much in my search and am also interested in any recent experience on the topic.

Would be really interested to hear thoughts, opinions, and experience with this.

You could request the serial numbers then contact the manufacturer to find the born on date.

Not always possible, but doesn't hurt to try. 
At times I’ve emailed the company that made them to see if they have replacement parts. Some good manufacturers tweak parts so they can’t always be found. Many use stuff that you can buy for $300 and pay $3000. This is a tricky business because many dealers typically don’t want to help with cheap repairs to non retail paying customers. Some in the business won’t support products from a second owner.  After some time you see the ones that work and support and the ones that mooch off supply line.
Used speakers with sealed enclosures are less likely to have internal insect and/or rodent damage.    
Any of the brands you mention in the 4-5yr realm, even 10-15yr realm will be fine and can be had for decent $$$. As long as they weren’t abused or subject to some other nastiness you’ll be fine.
Bought a pair of MTX Blue Thunders in 1992, 10 inch woofers, still kicking ass all these years later. Purchased a pair of JBL 8 inch woofers at the same time, 10 years ago the JBL surrounds of butyl rubber were shot, they also featured reverse phase, ie. the positives markings were actually negative, a nine volt battery test confirmed the polarity. i now prefer the rolled edge woofers over foam. I have experimented with a variety of woofers from different manufacturers over the years. Cerwin Vega rolled edge, Kicker rubber, and MTX rubber have stood the test of time. I have a pair of EV 12 inch 2 way horn speakers that were born in the late 60’s and still sound good. The vinyl wrap is peeling, but the speakers still work well. Some speakers age well.