You might check out DN42, it's a collection of people that connect to each other over VPN, and then peer with BGP to distribute routes. They have a pretty good copy of the internet, with root name servers, IRR and some L2 IX Fabrics. Getting IP space and an ASN is as easy as filling out a web form, and peering is as an email or IRC message away.
I believe the great learning part of DN42, on top of raw BGP knowledge, is working with other people. When you have to interface with another human, who controls a z-end that may be implemented entirely different than your own, it brings a lot of interesting lessons to the surface that you don't find when you do labs alone.
There is a network that uses VPN + BGP to create a mini internet inside the internet. It's called DN42. they link a bunch of hacker spaces where people learn this stuff from around the world. If you are interested in learning some of these technologies check it out.