The folks over at Boston-based RR Auction sold the awesome rock artifact for a cool $150,986. The notebook paper -- with lyrics written out in cursive (there's a lost art) -- has a back story that goes beyond Prince writing one of his biggest hits.

The fan who forked out the dough also got a detailed letter of provenance from Prince's former assistant, Therese Stoulil, explaining how she came into possession of the lyric sheet.

She says, "There was a knock on my door, and I looked out the bedroom window and saw a black BMW in my driveway and immediately recognized it as Duane's, Prince's half-brother."

Therese adds, "I went downstairs opened the door, and he only said 'this is from Prince' then he got in his car and left. Once I realized what Duane delivered, I was both stunned and humbled."

The sheet still has the white console marking tape Prince use to tape the lyrics to his mic while recording the track!

Although Prince wrote it, "Nothing Compares 2 U" was first recorded by The Family -- a group he formed -- for their 1985 self-titled debut album. Most famously, Sinead O'Connor covered it 5 years later and it became Billboard's "No. 1 World Single" of 1990.