I don't think Zlatan himself is a mercenary, not the impression i've got after following him since he played for Malmö and all the interviews he has given. Can't blame him for turning down a lot of money, it's not like he want's to go to Russia or China.
His agent Raiola though, cunt of the highest order, but apparently he's good getting money off other clubs for his player (and a shitload himself)