I opted for the 2011 mbp 15" for college for the bigger screen real estate because I wanted to be able to read a textbook on one half of the screen while writing on the other half.
However, its been two years now and my eyes have definitely grown tired of reading from the screen. I tried an iPad but it is inconvenient to carry a phone, a tablet and a laptop everywhere you go.
That being said, I wish I had the retina mbp. I would personally go for the 15" rMBP but in your case due to the budget, I would go for the 13" rMBP. The resolution difference is significant (at least in the 15" i haven't looked at the 13").
I also never worry about storage space on the computer. There is so much online storage nowadays that it isn't really a problem. If you want to carry a huge movie library or whatever just put it on a flashdrive or external HD.
Happy shopping!