Everything I know about Kubernetes I learned from a single-node (pseudo)clustered refurbished ThinkPad X201.
It cost me 90€ at an IBM refurbished sell. It is downstairs by the router, and it has been hosting everything for me except my email and my blog (which I want to host but I'm not sure about the reliability of my ISP's service, this morning it went down for 5h12m, without prior notice or anything).
It is amazing how much you learn from doing stuff. I'm currently on my 3rd year of univerity for CS, so I've tried the academia-style learning process, reading books on my own and doing stuff on my own. The latter is the best method by far.