If you bob the fenders keep in mind that the longer the piece of unsupported fender, the greater the wiggle. Although greater wiggle is something most of us would like in our female friends, you don't want it in a fender. I'm not saying don't bob it, heck, I just built a Speedster with bobbed fenders. Just keep it functional. Some other ideas:
1) Keep an eye out for other $10 bikes to use as parts. Colleges are filled with bikes abandoned from former students and the schools normally sell them extremely cheap. I would bet if you could locate the university surplus department and ask them in person if they could give you a couple of abandoned bikes that they never could sell, and that this was a birthday present for a friend, they would give you some freebies.
2) Ask art majors or graphic design majors for ideas. This site is also a great place for ideas and many a bike has been built for a girlfriend here.
3) Use her favorite colors on the bike, and try to incorporate her interests or personality in it somehow. Women looove that stuff. The dollar store and crafts store can be a source of inexpensive, whimsical items to throw on the bike.
4) If you need more space, find the smallest guy in the dorm and demand he keep the bike in his room....and get his lunch money while you're at it.
5) You won't need too many tools, but you'll need some. At a minimum, screwdrivers, a hammer or rubber mallet, and two wrenches. A can of WD40 wouldn't hurt either, but you won't need the whole can.
6) Sharpies and paint pens make for cheap pin stripes. You can borrow this stuff from the art majors or the wimpy kid in the dorm holding your bike.
7) You might want to buy a lock for your friend to use, since bikes are often stolen at college and you probably don't want to give her a present and then have to say "You'll need to buy _____ before you can use it".
8) Bicycle laws vary by state, city, and county, and the college might have a few of their own. You might likewise want to take care of the safety-related ones for her before giving her the bike, things like lights and reflectors. They're fairly cheap at places like Walmart ,and even more so if you get a parts bike or the dorm has more than one wimpy guy.
Good luck with the build!