Most of the top finance journals charge a huge amount of submission fees to submit a paper in their journal. For students, it is very expensive and demotivate them to submit their papers in top journals due to higher submission fees.
The submission fees to some finance journals are very high, even for re-submissions of revised papers (seriously !), as it is perceived that many papers in finance emanate from Business Schools, where the salaries can be high relative to most other disciplines.
Student discounts will not generally be available unless the paper has a single author, namely the student, and even then are not likely to be granted.
One never knows, so it would be prudent to write to the Editor of the journal with an appropriate request.