+1 sounds about right. My offers were 80k to 120k. (I'd say I went to a pretty decent university, but I wasn't too amazing.) There is massive massive variance based on the kind of position you are talking about.
I would say your numbers seem about right, though with the caveat that CS graduates can end up doing all sorts of things from IT-gruntwork-level tasks to rank and file software engineers, all the way to, yes, quants who are offered lots and lots of money.
I'd take a gamble and say that the name of the unversity is much more likely to effect your offer than grades. And even then, it probably doesn't scale down. As a hiring manager, you either went to a school I recognize or you didn't.
I don't know if anyone ever looked at my GPA. (It might be on my resume, and "they" might have filtered resumes with some hard GPA cutoff) It usually came down to my interviews and such I think.
I would say your numbers seem about right, though with the caveat that CS graduates can end up doing all sorts of things from IT-gruntwork-level tasks to rank and file software engineers, all the way to, yes, quants who are offered lots and lots of money.