Graduate School Prerequisites

[Thorne]

Speaking generally, how do graduate schools view credits from ACE for graduate admissions prerequisites? 

Specifically, I want to get into a certain subset of quantitative academic fields (still deciding which) that tend to require maths at a higher level than I currently have credit for. 

To level my maths, I can go through some online programs that will take 1-2 years and cost a great deal of money that I would like to save for graduate school, or I can self-study and do courses at a lower price from ACE providers.

I'm kind of between a rock and a hard place, so any information or experience with this is much appreciated.