Hey kid! (okay, I shouldn't call you kid, but I'm trying to be encouraging)
Go for it. As the longish post details, there are lots of factors that go into the cost, but almost anything over 28 feet will give you (comparatively) lots of room (for a boat, not for land), and won't still be so large that it costs you a fortune at the dock.
Let me encourage you to go for it, as it sounds like it's just within reach. Definitely make certain to get a sound boat... most boats sink at the dock it seems. That would put a "damper" on your studies!
What brand/model to get? I think you need to start climbing around on some boats (boat shows are a good place), visit marinas and ask around. Once you have been on a few, you'll start to get a feel for what you like/dislike. Lots of this is personal. If you don't cook ever and don't make coffee, a galley won't mean as much to you as lighting, or a good sitting space for instance.
I think you may find a number of boats that might suit your purpose well. Standing room? Consider it... but it's not the end-all/be-all. Button up inside the boat and sit there for a bit to get a feel of what it's going to be like when it's a gray rainy day and you have to try to study.
Good luck. Let me wish you well. I think you'll do just fine!