The force driving server virtualization is similar to that which led to the development of time-sharing and multiprogramming in the past. Although the resources are still shared, as under the time-sharing model, virtualization provides a higher level of security, dependent on the type of virtualization used, as the individual virtual servers are mostly isolated from each other and may run their own full-fledged operating system which can be independently rebooted as a virtual instance.
Now, you can maintain a high level of anonymity by paying for VPS through bitcoins.
The main problem faced by users paying for VPS through bitcoin is the fact that while payments to VPS service providers are generally monthly, bitcoin generally does not support recurring payments. This is mainly due to the fact that bitcoin is a push technology i.e. a transaction which has to be initiated by the publisher rather than the client or the receiver.
If you are familiar with hosting control panels, shell commands, and you have basic server administration and troubleshooting skills, then unmanaged VPS is the way to go. Note that while you purchase self managed VPS, you should be capable of managing applications, software, services installed on your VPS. Also, you must know installation/uninstallations, resource monitoring, server performance tweaking and troubleshooting of any technical issues.