5 pounds or 5 dollars or euros per month would be completely unneseccary. Plus, Jan would be able to retire early if 20,000 plus members started paying a monthly fee like that.
But voluntary donations could be an option, imho.
That the site is down at the moment may have nothing to do with funding though. I guess we'll find out once it's up and running again. Let's hope that happens soon, because I'm suffering from withdrawal symptons. :p