All of my aires are over 20 years old now, and are doing just fine, at the takeout, I do pine for the lighter weight super puma, but I do love the lot of them. Prior to the aires I did get a leaky older hypalon boat that did not hold pressure while I was looking at it. It came witth a frame, 3 oars, a pump and other stuff for only 450 so I decided why not? Well. I should have gone with not, I attempted to recoat and seal it with a tolulene bath, and new hypalon paint, and that was a big fail. And even with a respirator and outside I had a headache for a few days, but my kids turned out normal, for the most part. If the material is supple, not cracked, and it holds air, and it is a good enough deal, I think it could be fun. Most of my river days are day trips, so if a boat stays hard for 2+ hours I can work with that. If it is multi days and it needs to be topped every hour, that will get old fast.
One big thing to look for is blown baffles. close all the valves and start inflating an outer section, and watch the other sections of the boat. If you can inflate 2 chambers from one valve there is a blown baffle. That is not the end of the world, but they are pretty impossible to repair, and if either chamber is compromised both are gone. If it is more than one blown baffle, I would walk. having a single chamber 16 foot raft will be great until it isnt, and then it will suck on a level of kidney stones and jack fruit. (which really sucks. )