If you want to play the piano, you must get yourself a piano.
It is fun to learn Cisco stuff but without access to their proprietary toys, you can learn the basics but you can't become a virtuoso, can you?
So what's the alternative for my restless mind?
OPEN SOURCE SYSTEMS BABY!
Quick assessment of the situation:
I have two Raspberry PI computers running Raspbian OS, and a salvaged old Dell Optiplex 745 tower that was being decommissioned and doomed to be scrapped. It has 4 GB of RAM memory and 80GB HD. It's enough to install ... KALI LINUX.