Back to the subject of where to find tango music, look at this! This is fun; Last.FM music-on-demand. You can make radio stations. And you can also buy music.
There's one generated by a "Tango-DJs" group, but if you try to skip a track, it tends to start playing awful rock, or Shakira, for no very obvious reason. So instead I've embedded one that plays what people on the site have tagged as "tango".
The tango-dj one just played me something I sort of like, and haven't heard before, and wouldn't have bought after looking at the cover; but I might, now. Well, maybe not this one (Gotan Project tends to get on my nerves after the first eighty seconds), but one of them.