Even if albums are digital, nobody can expect them to be available 'forever' imho...
OOP is an unfortunate expression here but would be more appropriate anyway.
Maybe just some shop links and OOP checkbox would be better...
I've added several Amazon ones.
btw off-topic: is it finally time for (mainly) US Amazon links to become visible again?
...this little shop still has some of these albums (or so it seems) but mp3 purchase is limited to the USA so I wouldn't know what's the deal.
http://www.davesmusicmine.com/Artist/1054615