I'm sure there's been a post like this already, but I am currently trying to find ways to practice stuff at home while not breaking the bank. I am using cisco Packet tracer for testing and playing around and I've been thinking about buy a Raspberry Pi or two. I'm just curious if there is anything in addition I could do until I have more money to but some nicer stuff.
If you have an old PC, that could very well be a start. Otherwise, Dell Optiplex or Intel NUCs will be more powerful than Pi at the same price. Throw Proxmox on it and you have yourself a homeserver.