If you have funding to support the other 50% of tuition and the life in NYC, it could be a great opportunity. But I do think that a MA, for instance, in eco or data science, would be a better background to apply to phd programs with high quant approach. I would suggest to speak with current and former MA students and faculty members to assess whether this option would work given your interests.
PS: For the extent that I know, the MA students do not have the 50% discount.