I went to grad school (science field) in a small college town where there was certainly some cheaper boarding around- and I would have had the time. Grad school is a little different now. Lots of work but you can do so much more from home than even 15 years ago. That kind of gives a flexible schedule which is helpful for getting in riding.
Its possible depending on where you go and how much your stipend is. My stipend was pretty low so I had no extra $$ for anything but i think they are better these days at many places.