Yes, it probably is, but factor in the production costs and other cast members, and those 12 stars are getting, what, $3-$5m each, which is fair. Still a bargain for that cast me thinks.

Statham, Stallone, Lundgren, Li, Couture, Crews, Hemsworth, Schwarzenegger, Van Damme, Willis, Adkins, Norris = 12 big names

Divided equally, that is $7.5m each, which is a bargain for most of those names. Not to mention actual production costs and other cast members and everything else that goes into making a movie. I think $90m is incredibly SMALL for The Expendables 2.

Sure, it's bigger than TE1, but still a cheap picture by how much money the movie can make.

Oh, and lets not forget the fine for killing bats.

Couture, Crews, Hemsworth, Van Damme, Adkins,= not big names and faces I would not be able to pick in a crowd.

Divided equally, that is 12.9m each, which is way way too much for most of those outdated names, as clearly demonstrated by the gross of the film.
It's high in reality. It's high in relation to other films given the narrow(ish) scope and limit of the type of action, this isn't Avengers sci-fi war shit. It's just guns. 90m isn't terrible and with overseas the movie will make a profit, but it's higher than necessary and won't make a lot of money partially because of that.