Idiom "for a song"

FOR A SONG

What does the idiom, to get something for a song mean?
When you get something for a song, you are able to buy it for a low or discounted price. The nuance is that instead of paying money for something, I just needed to pay for that with my singing! I got it for a song! (OK, maybe not my singing, but you get the idea!)

• I got those sneakers for a song at the flea market.
• In Chinatown in NYC you can get a great meal for a song.
• You can get the lucky eye charms at the Grand Bazaar in Istanbul for a song.

How about you? What have you gotten for a song recently?