It wouldn't need to be anything top of the range. It just needs to have the same ISA. At home I'm fairly space limited - one small office that I share with my wife that has 3 desks. I have 2 old HP workstations, a MacBook and my Dell work laptop when working from home. I may replace the guts of the elder workstation one day, but as long as it is still working I'm not too motivated.
Most of my work on Valgrind I do either directly on the workstations or using VirtualBox. I might also give QEMU a go, but running Valgrind inside of an emulator isn't too likely to be a happy experience.