Speaker life expectancy: How long can you buy used

I'm in the process of assembling a cost-effective second system with high quality used or demo gear for use in a relatively small room (appr. 20qm, normal height, wardrobe, big window, carpet, sofa, apart from the size of the window quite average really).
I saw a pair of Avalon Monitors, that I think could fit the bill at 30% of the original price, mint by the looks of them BUT seven years old! In spite of the good things I hear about Avalon's longevity, I do wonder whether it is wise to buy a seven year used speaker, any speaker.
Apart from considerations of wear, where would you draw the line that even a steeply discounted speaker of justified fame in its own time will likely not be able to compete anymore with new products that may cost just about the same amount of money, new that is. And are there exceptions to the rule?
Any considerations or experience you may want to share?
Speakers and their crossovers are good for decades. The foam surrounds on older speakers may rot after 10 or 12 years but that is easily replaced with modern foam which is good for 20 years or so.

The crossover components should be replaced by thirty years. I say that but until recently my computer room had a pair of Dynaco A-25's from the early 70's that sounded good. They still have the original parts in them.

So the moral of the story is speakers don't really wear out. Now there are stats and panels that do have issues much earlier but that's a different subject.

7 years is a non issue. The speakers I'm listening to now I bought new three years ago. In 20 years it may be a problem somewhere. There's alot of speakers from the 70's that work as they did new.
I know this flies in the face of everybody else's experience, but my Advent New Large Utility speakers, which I got new in 1978 (!) still work fine. The tweeter level switches need a cleaning (I think), but so far, the foam woofer surrounds are in tact!
a lot depends on the actual speaker components. SOme speakers have a foam that breaks down pretty easy. Other designs this does not appear to have a problem. lots of altecs, jbls, klipsch speakers out there that push 30-40 years and still sound good.
I just pulled my very first set of speakers out of storage. I haven't heard them in 20 years and they have been in storage for 12. I Am happy to report they work perfectly. Frazier Concertos- 10" woofer, 3x5 horn, dreaded piezo. The pleated surround on the woofer is in great shape and the 32+ year old speakers sound better than expected. My 12wpc t-amp plays as loud as I will ever need. I'm really enjoying them.