again..it's a ladder model for actors getting paid low sums upfront then more money later on.. I'd say the Guardian actors would get paid well on the backend if the film makes around $500-700m worldwide.. that's decent figure considering it would need to make around that to cover production/advertising costs.. not sure why any audience member should really care how much an actor makes.. it's more important about them being right for the role.. also it would be fun to ignore this "fact" but DISNEY OWNS MARVEL AND PAYS FOR THE PRODUCTIONS NOW POST-AVENGERS.. Disney spends over $200m on giant flops films ..to think they wouldn't give Marvel (who has a massive proven track record with hits) extra funds if they really needed them to secure talent.. Disney just bought Star Wars which just shows how much money they have to blow.. they're possibly spending Marvel-sized money on Brad Bird/Damon Lindelof's secret sci-fi film.. this isn't Marvel doing it on their own and partnering with Paramount to distribute anymore..
also if you look at other "big" films I doubt there were salary demands during the contract signings for Lord of The Rings, Hobbit (besides returners), X-Men 1, Avatar, Star Trek reboot and kill me for referencing Twilight..however, I don't think a lot of the leads of those films are starving or ranting about they got screwed out of millions.. it's exposure and an interest in the material that would drive an actor to want to join a film like Guardians of The Galaxy.. if an actor was only in it for the money then you'd see that on screen and it would be a wasted performance..