I'd want to walk away and be able to look someone in the eye and say "I'm a dot com millionaire." So with the share structure, capital gains tax (guessing), and exchange rate the number I'd pull out of my ass would be four million for the whole shot assuming no dilution.

Three months is long enough to know if I really believe in something or not. I wouldn't sell out on anything I believe in for less than this. If that money isn't on the table after three months, I can wait and put in the sweat and time to make it worth that much.