My opinion is always

a) ask for a higher pay than what they offered during interview. This is the best time to negotiate your pay.
b) if you fail to get it, take the job if you like the job and ask for the raise upon confirmation.
c) if you fail on both attempts and think you deserve better, quit and get another job.

Bottomline, no one will make it "fair" for you. You have to fight for it.