All of those are clouds, not really meant as an always-on home in the cloud (or at least an expensive option). I'll assume you are looking for low-budget since you mentioned "Academic project."
What you are looking for is probably a VPS (can be had for < $10/month at many, many places) or simply setting up an old computer on your home connection. Even if you have a static IP, use DynDNS or similar service to get a static address to connect to.