Well, you can set up some headless mac minis and run a variety of virtualized OS X instances on them.
I personally don't see the advantage of using other hardware, Apple hardware is a better value to me. (I value reliability over lower initial price, and I don't find generic PC components to be cheaper for the same thing, nor to have adequate reliability. )
That's pretty much what I've done when I needed to, don't get me wrong, I like Apple laptops and will be replacing my recently stolen Macbook Pro as soon as my budget allows; but being unable to launch an OS X vm is an inconvenience at times, and a completely unnecessary limitation.
I personally don't see the advantage of using other hardware, Apple hardware is a better value to me. (I value reliability over lower initial price, and I don't find generic PC components to be cheaper for the same thing, nor to have adequate reliability. )