本人,PhD. from top 20 school (UW) in the U.S. My tuition was waived and I paid just a few thousand dollars per year for on-campus housing, health insurance premiums etcetera so it depends on your funding but at least my cost of living is very low as well. In Europe where PhDs are more common there’s free university education too, although that doesn’t mean you won't pay anything out of pocket to travel back home every now and then and do summer conferences with other fellow students because they might need an airplane ticket too! The only thing I don’t mind paying extra when I can afford it is research costs like conference registrations and traveling expenses – these were never much either way since our program didn't have any mandatory field trips or international meetings!
My advice: be honest about what kind of opportunities will be best for you in order to make sure you get a realistic estimate if you think this may work financially for you; ask potential advisers how likely their department would approve applications, given the fact that some fields/departments prefer candidates from certain universities than others. Good luck! (I am not affiliated with anyone who asked me to answer here honestly)