Both Amazon MP3 and Wal-Mart have raised prices on select digital songs following the iTunes Store’s move to variable pricing yesterday. Select tracks on Amazon’s MP3 store are now $1.29, matching iTunes’ top-tier pricing, while Wal-Mart has raised certain songs from $.94 to $1.24. Amazon’s decision to raise prices may seem unusual given that the service actually cut the price of many top-selling songs in its UK store ahead…
