Maybe this depends greatly on the particular discipline you're in. In the US it's not that difficult to get your Master's degree in C.S. for free + monthly stipend, at least in my experience.

I know a number of people across the natural science disciplines who TA'd / RA'd their way through Grad School. I might be misunderstanding how common this is but it seems any discussion of Grad School cost should discuss the fact that natural science students will often get paid to go to Grad School in the US.