All higher education is expensive. A postgraduate education is even more costly. Exactly how much more depends on the school you choose and the area where that school is located.
Say you want to matriculate at an Ivy league school for your PhD degree. What the heck, let's live dangerously and go for the best and say you want to go to Harvard! A PhD student at Harvard is charged full tuition for the first 2 years (currently $37,576), reduced tuition for the next two ($10,112 as of 2013) and a facilities fee thereafter until he/she graduates ($2,574 as of 2013). There is usually a 4-6 percent inflationary increase every year.
Added to the above, you have to pay the mandatory health services fee at $956 (add another $2,190 if you want to go for the Supplemental Blue Cross Blue Shield and Hospital/Prescription plan). Of course, you have to live somewhere and eat something. Locales in the northeastern United States have a higher cost of living than most other places, so if you go to an Ivy league school, you will end up paying between $20,000-$25,000 per year on accommodation, utilities, books and supplies and other miscellaneous expenses.
If it takes you 5 years to complete your program and earn your PhD degree, you would spend at least $200,000 before you graduate.
At a state university in another part of the country, the average cost of a PhD is about half of that.
And that is only your cost in terms of money. The PhD degree will cost you around 5 years of your life. It will cost you many sleepless nights of study. There will be times of desperation and depression when the research is not going too well. There will be impossible deadlines and terrible stress. There will be several severe tests of your character and motivation.The PhD will cost you in many ways that you can't quantify and ask the bank to calculate!
If you're willing to pay the qualitative, intangible costs, however, you really don't have to pay for your PhD. In fact, you will probably get paid by your school or department while you go about your studies. If you are accepted into a PhD program, you are likely to be granted financial aid in the form of a Teaching or Research Assistantship. Additionally, you are free to work 20 hours a week on campus during the summer months and breaks if you stay at school and register for a couple of classes.
The stipend from the assistantships may not be too much, but it is enough to cover your fees and your basic cost of living. As far as tuition fees are concerned, the policy differs from school to school. Some universities may waive your out-of-state fee, others may waive tuition fees all together and charge you just a nominal flat fee per course. In sum, you won't be rich and you won't have a lavish lifestyle, but you won't starve and you will be able to afford a pizza now and then!
Even if you don't get an assistantship immediately, don't lose heart. You will easily find on-campus jobs if you are determined. Also, there are always scholarships, grants and awards that you can apply for. At worst, there are student loans that will help you pass the initial waiting time until you get your bearings and find the assistantship or on-campus employment that will take you through the program.
A PhD, even at the best, most expensive university, need not cost you any money at all once the school accepts you as a student. You have to be willing to pay a steep price in terms of your life and your relationships, however. There's no way out of that cost.