The Eugene McDermott Library does purchase textbooks, but it's only undergraduate core textbooks. Those textbooks have 2 hour library use only. Previous editions of textbooks can be found through the library catalog with a title/author search.
There is also the possibility of a textbook known as a "course reserve" at the Circulation Desk for 2 hours use in the library. These books can also be found with a title/author search in the library catalog or by checking the Reserves by your professor's name or class number.