Creating Packages – Sandbox? Virtual Machine?

Hey guys, I've been looking into a method for making packages where I could create a package, upload it to a server and then go back to before I created the package to create another one. Basically, I'm looking for VMware-like VM snapshot functionality. How do you guys handle making packages? I've currently been using composer to make packages, then reimaging the machine and making other packages. I basically want to keep the system clean so that I don't have any random issues with the packages I create. I REALLY wish I could run OS X in a virtual machine, but I know Apple doesn't allow this in their ToS, so I thought I'd ask how everyone here handles this. Thanks, Nate