I have a friend who, like me, is a Math major, although she started later than I did and as such, hasn't yet gotten into the core classes for her degree. She's frequently checked out my own personal library and I figured that, since the holidays are coming up, it might be cool to start her off with a small collection of her own. So, basically, I want to get her three books, one for each of the core branches of math she'll be studying over the next year and a half. However, I want to keep it affordable, so I'm probably most interested in finding her good Dover books on analysis, algebra, and topology (although if there are good non-Dover books for around ten dollars apiece, I'm open to those suggestions as well). Do you guys have any helpful suggestions for me?