A caveat though. Using the bill the pay for the test will use one month of benefit; no matter the cost between $200 and $2k. Compared to a month of college+the living stipend, it's monetarily not worth it if you have any other options (which you do).
A better route would be leveraging the IVMF program from the University of Syracuse. Depending on when you separated/retired they have sub-programs that you can apply into. I'd highly recommend starting there. If you're accepted into the CISSP track and complete their provided training, they'll provide you with a voucher for free.