Welcome Jean, others will help out with a fair price, I don't keep up with those things. As far as there performance just check " by ear " that each individual driver/speaker is working, you can cover one and listen to the other.
That should cover most of it, after listening for a while to get an idea of how they sound you should probably look into refreshing the crossovers, this don't have to be expensive if you just replace the caps. Thats the main parts that change over time, there are many Cornwalls out there that are MUCH older than those, they will probably outlive you !
Others will be along with different opinions, all in the same general area, it's a safe buy, as far as there age goes that is not a problem at all. If the price is fair buy them, that's my thought.