Cover version cds sold in Singapore

pu2, an Indonesian studying in one of the universities in Singapore, discovers dirt cheap CDs being sold here. The catch is it isn't the original artiste who is singing but some other dude who re-recorded his songs. From pu2:

Yesterday I went to one of Singapore's many shopping centres. At the ground floor, I couldn't help not to notice a very big, enticing sign. It said, "CD Sale - $3 each!" There was even a crazier price tag below it, "$1 each for 5 CDs!" Drawn inside by the very cheap price (as one CD would normally cost you $20 - $25 here in Singapore), I glanced over the plain of CDs, arranged on a very big table.

The names on the CD covers seemed promising: Michael Bolton, George Michael, ABBA, Coldplay, even Robbie Williams and Norah Jones to name a few. But then, I noticed something peculiar about the covers: I'd never seen any of them in any other CD store! All of them were also labeled as "The Best of" albums and I noticed that The Best of George Michael had a rather pixelated photo of the singer on its cover.