[Tango-L] Tango CD/iTunes collection recommendation?

[KUROSAKA Teruhiko]

I was asked by someone who just started tango what tango songs
he should be listening to.  But I don't have a good recommendation;
I myself bought tango CDs pretty randomly and my collection still
lacks many of the popular songs I hear at milongas.

Can anyone recommend a few compilation CDs, iTunes song
collections, or any other source that beginners should purchase
first?
-- 
KUROSAKA Teruhiko ("Kuro"), San Francisco, California, USA