I'm creating a hosting company, like Heroku and can't be hosting my customers stuff on another company's servers, thanks for the advice though. Also there are some cheap $99 servers that might get the job done.
[1] http://www.ravellosystems.com/ [2] https://code.google.com/p/xen-blanket/
If neither of those things is true, then you're probably better off waiting until you can afford to make the investment purely out of your profits.
Of course an alternative is to just get dedicated servers without having to worry quite as much about managing your own hardware.
Disclaimer: I probably don't really know what I'm talking about :)