I am frequently asked where to buy certain albums, etc. There are many online stores that are well worth trying. I can't begin to present a complete list of such places; instead all I can do is list the places that I have tried (or that I know other people have used) and that are worthy of recommendation.
Note that these vendors pertain to legitimate releases only. Please don't ask where you can buy bootlegs. You could try the small ads of a traders magazine (such as Goldmine) or have a good look around at one of the larger record fairs.
A few of the smaller labels can supply direct, so if your local store doesn't stock a particular item, you can order from the label direct.
Cherry Red have put out a couple of relevant releases, as well as publishing the excellent Biography.
Since I live in the UK, I can only list those UK sites that I have tried. It has been many years since I bought from the USA, so any list I present of US sites is likely to be woefully inaccurate.
I am sure there are others; but I don't want this page to become a list of every commercial record store with a website. Just start searching from the usual places, I guess...
Yes, it is a sad fact that there are several Mott The Hoople and Ian Hunter CDs that are out of print. Many stores appear to list them, but placing an order is likely to result in a message of the form "sorry, we cannot supply that item".Adrian Perkins