Hi Azm,
Let me jump in on Cisco VIRL. I can highly recommend to run it in VMWare ESXi, it’s free and saves you the hassle of messing with network interfaces etc. Although I really like VIRL, I had some issues with updates that went wrong and deploying a new OVA template in ESXi is much easier than reinstalling a physical box.
Look on eBay for an older server that has plenty of RAM and 2x CPUs or something like that.
I still use an HP proliant DL360 G7 with 96GB of RAM which is great for Cisco VIRL:
$325 for 8 physical cores (16 with hyperthreading) and 64GB RAM. What I like about HP / Dell / any other vendor server is that VMWare ESXi works out of the box…no issues with drivers or anything like that.
Rene