Earlier quoted context omitted.
Why would you really need physical machines for linux and windows, you can always virtualize clients and run dual boot mac/windows or single thinkpad with win/linux dual boot. If budget is tight used servers are great value, for example del R710 is cheap with plenty of horsepower. Downside being space and sound.
I prefer getting a really powerful workstation and doing virtualization from there. Example: http://natex.us/enthoo-128kit (No affiliation with Natex, but I've bought that kit and I enjoy the overkill of 16 cores and 128gb of RAM)
Re: Building a Home Lab for Offensive Security and Security Research
#21Price has jumped a bit from your presentation.