OK, this is sort of a catch-22 situation, but many colleges and universities offer free or reduced-cost classes to employees. Of course, you have to be able to get a job at the school to qualify (catch-22). It is a thought, though. I started working full-time at the University I am attending, and get "free" classes, up to 6 credit-hours a semester. I work in the IT department, and am working on a degree in experimental psychology and taking music classes as well as whatever interests me. I am a "traditional" student in the old sense of the word... I'm there for an education, not a career. I like to learn.
You would have to find out what the criteria are for an employee to qualify, but I believe that at most schools that do this, any full-time employee would qualify. So, if you have any skill or experience that could land you a job in a given school, you can pursue your interests. Examples would be building and lands maintenance, custodial, general office skills, computer skills, admissions recruitment, etc. In other words, you don't have to be a teacher to get free classes.
Also, and separate from the above idea, look into "continuing education" and "life experience" credits. The latter could potentially decrease the number of required courses (usually with an interview or exam), and thus lower the total cost a bit.