I've gotten a lot of useful knowledge through old "throw-away" equipment, or still-usable equipment that was being set aside for new...a tinkerer's mindset. White papers, old manuals and books, any information that can be gained online or through colleagues, etc., are also great ways to learn things on a budget. Salesmen can also be a source of education, too, as they are usually knowledgeable about the routers and other hardware that they sell. Free downloads and demos are also tops! Load them into a virtual machine and learn to one's heart's content. These are pretty much "no-budget" ways to learn, but they work well.
(I'm open to the article idea with Jessica.)
One way I’ve learned was use existing computer equipment (old pc’s), install nics (2 ports needed), and various flavors of Linux. You in essense would turn a regular PC into a router/firewall. Now using another machine, you can use a free virtualization product of your choice. I’ve used Ubuntu on a laptop with VMware Server. On the laptop, I have various systems configured but due to CPU & Memory restraints, I would only turn up 3 VMs at a time.
I would started to volunteer or do co-op at companies like Cisco or IBM on they community projects.