Places to Buy Vintage Recordings On Line
Here are a few places I know about where you can find vintage recordings from the first half of the 20th Century.
First, iTunes has a modest assortment. The main advantage of iTunes is, of course, that you can buy a track at a time, and don't have to get a whole CD that might duplicate items already in your collection. The best way to find stuff is to enter the name of a well known artist like Duke Ellington, and then look for the links to collections and "mixes".
Amazon also has a modest collection--but just as it is shopping at a brick and mortar store like Borders or Virgin, you will generally only find the big names with a few obscure treasures here or there.
Fortunately for the lunatic fringe like me, the internet has a few sites that address our needs.
Worlds Records
That's enough to start. Please use the "Comments" function to suggest additions to the list.