It's beem confirmed to be 400k. The Prima book was wrong (what a surprise). If you donate 500k (like I did), you'll get the fountain, but lose 100k. :(
lol I voted "Coffeh, I love yew". :P
Um, I never set letters to meh future self, cuz I don't see teh point in it. But
I think I might try it today. Eh... :)