I'd recommend buying from the TechCyte area in the ISU Bookstore. They offer pretty good deals to students. However, you may have to wait until she is officially a student.
Tech CYte - Home
The best thing about buying a Dell through the University is the warranty. You have to pay a little more than you would buying a refurb or whatever, but you'll get a no questions asked replacement policy, and she can get it fixed right on campus by the University, for free. It's definitely worth looking at, although the price is going to be a little more than what you've stated your range is.
For those who don't think warranties come in handy: You have no idea how many times I had kids come in and tell me their "roommate" spilled "something" on their keyboard and fried a bunch of stuff. Trust me, it's worth it.