I didn't get too many books for classes during my undergrad.* It was nice having the same major as my SO who was two years ahead of me! There are at least 4 books I didn't have to pay for because of that. In addition, I used a lot of PDFs. I've only ever had to buy something like a book a semester! It's pretty nice, because I get access to a lot of resources without adding any bulk. This semester I'm using one borrowed book, one PDF, one bought book (used, very cheap!), and one of my classes has readings uploaded for free.
*Actually, I lied, I had a bunch from my last major (Russian)... But those I keep at my parents' place.
EDIT: As far as actual advice for OP... Only keep your favorite books, or those most relevant to your graduate education, especially if the information is timeless. You can look for free digital resources to compensate for some books as well. Maybe try to give the ones you don't exactly need but don't want to get rid of to people who are close to you so you can have access to them again if the need ever arises, or if you move back into the area.
Also, I'm ready for the comments about how people prefer actual books over digital media. XD