>Eventually I plan on going back to a real University and getting a CS degree, but I'm unable to do so at the moment

Come up with your own curriculum then. Invent homework assignments like the following:

1. Install a linux distribution: http://www.ubuntu.com/desktop/get-ubuntu/download

2. Install the languages you mentioned: sudo apt-get install sbcl ruby

3. Type 'irb', 'python','sbcl' to open interpreters for Ruby, Python, or Lisp

4. List the names of all the data structures and algorithms you've heard of and their operations. Be sure to include hashtables and b+ trees.

5. List the worst\best\average case runtimes for each operation.

6. Describe a practical use case for each.

7. Implement each by typing directly into one of the above interpreters.

You'll learn much faster, always get A's, and not have to spend any money.