Going to start studying towards my CCIE in a month of two and going to use this blog to document my progress.
I have a HP microserver N54L (picture below) that I picked up from eBuyer for £99, IIRC it was £199 with £100 cashback. I also spent some money upgrading it to 16GB of RAM. I have installed the ESXI hypervisor onto the server and plan to run as many Cisco CSR's (Cloud Services Router) as possible. I can use these virtual routers within my CCIE lab.
I will be making a blog post shortly documenting the installing of the CSR and how many I was able to install on the server, the last time I checked you needed at least 2GB of memory per router but I want to try and get at least 10 installed.