It really depends on the field. There are a lot of free ways to learn about a subject that interests you. Websites like coursera have free online college classes, and you can find a lot more from the colleges themselves with a bit of googling around. You can also get library books and audit college classes. Depending on where you live, there might also be free lectures on different subjects. These will be listed in a local newspaper or on the activities board at the public library.
In an area like psychology, you will really need to have a degree to get a job. But if you have a lower income, you could qualify for a surprisingly high amount of financial aid. My suggestion would be to apply to a few colleges and talk to a counselor and the financial aid office.
There are a few subjects that you can still basically teach yourself and get a job. Off the top of my head, I know of two. I got my foot in the door with a part-time job at a wine shop and studied A LOT in my free time, mostly with library books. That led to my current job managing a wine store. From there, a lot of people go on to higher positions in the industry. One of my college dropped out and taught himself to write code while working at radio shack. He had a nighttime tech support job for a while and then got a great job with a government contractor.