You are asking for too much for too less. Let us know if you find something.

Best case, you might be able to get some discount for being a student (provided your school has some deal with ATT or TMob). ATT gives us 20% discount for our school. If you are not a student, there are other discounts for certain companies. 

Better yet, forget family plan and go with individual prepaid, STRAIGHT-TALK from Walmart. You get Unlimited everything for $45 (the data plan is not quite unlimited, can't stream audio/video). But then the phone is not GSM.

Good luck.