Where can I get a cheap, virtual, high-performance server suitable for academic use?
In most countries, there exist high performance computers that researchers can apply for access to.  For example, in Sweden there is the National Supercomputer Centre, and other countries have similar projects.  When you get access, you get a limited number of core-hours (for example, if you have 5000 core hours, you can run 50 cores for 100 hours or 500 cores for 10 hours) to be used over a specific period of time (for example, one year).

To apply for access, you may have to go through someone who is employed at a university, if you aren't.  If you are a student, you hopefully have a supervisor who can apply for your project.  Or they might have special services for students!