Ask HN: How to go back to school?

I graduated in 2010 and I'm currently working in a sort of junior developer position. I have a math background but I've found that an engineering master's is required for many of the jobs I'm interested in. For those who have done it or have some knowledge about it, what's the best way to go back to school, financially? As a non-degree seeking student initially (as I'd be taking undergrad prereqs) I know I won't qualify for certain financial aid. Any advice from those who've bootstrapped through something similar is much appreciated. I imagine this question could be helpful to many in the future as well. Thanks for your input.