Thank you Sue for the reply,
The reason I feel that I have a better chance in the top 50-100 program is because, as mentioned, I goofed up a little during my graduation. Although i did make up for it later on during my MBA, but I still feel that this shortcoming might affect my chances more at a top 20 program. Moreover, all the top 20 programs state that the average GMAT of incoming students is 720-730. This is another reason why I feel I might not have a chance. Thus, I have shortlisted Universities which have average GMAT scores in between 680-710.
As far as my reasons for PhD. in finance is concerned, it is the next logical step for me to further my chances for growth in the career that I have chosen, Academics. Moreover, I have really started enjoying research, even though I haven't yet published a research paper, but I am working on a couple and the brainstorming it involves is something that I find to be fun, even though frustrating at times. I want to get better at research, engage myself in quality research and make a difference to my chosen field of academia. Thus, the PhD. finance.