to my knowledge stipend varies. the least i have heard is about $450 per month for 10 hr TA/RA and most I have heard is about $2000 per month for 20 hr TA/RA. This excludes tuition waiver. in some schools grad RA/TA dont need to pay tuition fee but in some schools they need to pay some percent of instate fee. every grad students need to pay regular other fees. if you get TA, there is also a chance that you will get paid for fall and spring only, you might not get paid for summer. bottomline, every school has its own rule and pay varies from school to school.