The salary cap on PwC Senior Associates in mainstream consulting is 45k - strategy may go higher however.
What exactly is your pre-MBA experience? If it's solid transferable experience in industry then there's no reason why you couldn't come in at Manager grade.
DO NOT fall for the trap of having to take the lower grade / prove yourself / try to get a promotion early. The min time allowed for a promotion is 18 months in grade, so you're looking at at least 2 yrs if you came in as an SA.
FYI - Manager grade goes from 48-65k.
If you feel you have enough decent, transferable experience then push for Manager and believe in your worth!