First Kid Rock, now AC/DC.  The longtime iTunes holdout is selling its new concert album, “Live at River Plate,” via the online retailers along with AC/DC’s entire discography – including “The Complete Collection,” which includes all of the band’s studio and live albums and box sets, for $149, and “The Collection,” which features its 16 studio albums for $99. Each of the titles has been specially mastered for iTunes. There’s no word yet on whether other digital retailers will carry AC/DC music in the future.