I also just completed the VCP5-DCV certification. I found my own home lab instrumental and purposefully built a lab just to practice with.
You don't specifically mention a budget in your original post, but I'll let you know what I did and my reasoning behind the decisions I made.
Basically, I started by picking a processor brand. I went with Intel because I felt that the Core i7 processors hit the right sweet spot between power consumption, speed, virtualization features and memory support.
Then I went to newegg and started looking at the available 'deals' they were offering. I found a great deal on what would have been a gaming package if the system had come with a graphics card, but since I didn't need the system for gaming, I saved a lot of money by relying on the on-board graphics of the i7 chip that came in the package.
Overall the package was about $650, for a gaming case, power supply, Mobo, Core i7-4790 processor, 8GB RAM and 128GB SSD. I also added an additional 16GB of RAM and an additional 256GB SSD. The processor will support an additional 8GB of RAM, and the package I ordered came with a single 8GB RAM stick, so it won't be as expensive to add that last 8GB of RAM. In total I spent a little under $900 for my system. Your processor will probably be around $200 for an AMD and $300 for an Intel to get the features and performance for doing a nested VM lab. I would highly recommend using an SSD, 256GB should be plenty for a lab as long as you are thin provisioning your VMs.
Let me know if you have any other questions or if you have a budget in mind so I can make more specific recommendations.