I have a barebones testing VPS, which, as they are insanely cheap, I think everyone should have one. True, these aren't really usable by retail website owners, but if you're in IT and take QA seriously they're wonderful.
The one big issue with these are having to rebuild them from scratch when you want to try a different set of software packages that will emulate a clean production build and configuration. The solution was relatively easy, but the journey was a pita.
SolusVM's Central Backup seemed to be the ideal solution, but, it's not: