Didn't Sagna only cost 2 mil? I don't know if there were clauses added on, but I believe this was the money paid without any...
As far as I remember, Vermaelen + Nasri + Walcott + Sagna + Clichy + Fabregas + Wilshere ~ 37.3 million (obviously, the last two were free). I don't know what Szczesny, Djourou and RVP cost, and I seem to remember a fee of around 200K for Song, but I'm unsure.