Have you considered moving the compiler to the client side? In theory you can build a C/C++ and virtually any other language compiler in Javascript.
Security restrictions on the browser might be an issue, but i think you should be able to store the binary output in the local storage and upload it to the server.
The fact that they plan to keep things running indefinitely if possible seem to indicate that servers and bandwidth are not the bulk of the cost
So I guess most of it is on paying developers and maybe some office space. 25,000 won't go a long way, even taking in to account cheaper salaries in Greece.
Edit: Their team page says they have 6 employees, so 25,000 probably doesn't go a long way.