I recently came across a steal. A friend on a social network posted that a recording was $6. That may seem normal for an mp3 release, or mildly cheap if you purchase an iTunes release for $9.99. But this particular recording was live from Bayreuth - the complete Ring der Nibelungen by Richard Wagner. Yes, all four operas.
The whole world has been celebrating the 200th anniversary of Wagner's birth this year (his birthday is May 22). Summer festivals have been playing his music, and several cycles of the Ring are programmed for companies this fall and winter.