First of all, you should be aware that evenyone's case is unique, and every school's admission policy is unique as well.You should figure out something for yourself. If I recall correctly, Duke once admitted one guy with GMAT 560 +-.
Secondly, I think one buddy above has presented a very good suggestion.
mauricewang and leighyao, thanks for your constructive advice.
I'd like to remind all the friends here that, to be honest, my question is only 'what should I do to offset my low undergraduate GPA'.
I really know that it is very very hard to get an offer from a top finance PhD program, but as mauricewang said, 'you needn't perfect'. I believe it. If there's hope, I will never give up.
You can make a professor with strong reputation in ur field write the reference for you! Anyway, in my mind, if you have a long-term goal, how come you just build up your background now? Is it kind of late? Anyway, good luck!
Rumor said there are 600 applicants for UIUC's finance phd, and 300 of them have 4.0 GPA. If you are a undergraduate, you must face tons of perfect or nearly perfect students in the fight for offer.
Be honest, if you don't journal paper or nobel level recommendation, your chance to get into programs around 50 or 60 is pretty slim. Even perfect GMAT or GRE couldn't save you because now everybody knows Asian applicants' grade is overvalued.
So, one way is to study in prestigous master program in U.S. (no matter which major) and get a perfect grade. A outstanding performance there could probably make committee ignore your seemingly lousy under GPA, and also it could earn recommandations from U.S. faculties.
However, I must warn you first that more than half applicants are doing the exactly same thing.
So you should set a further goal of pursuing nice research when you're in the master program.
A good paper could demostrate a lot of your ability and cover most of your weakness.