The key is, you should want to aim too high! They're not going to say 'no, and never darken our door again' (or if they do, then you had a lucky escape - if they're that nasty and irrational at negotiation time, what would they be like to work for after they had you in the door??)
They'll say some variant of no - 'that's a little higher than we were thinking of' or 'ha ha, very funny' or 'well we were looking at something closer to typical market salary' or 'I'm afraid there's no way our budget would cover that' or however they want to put it, the point is, they're not willing to go as high as the number you named, which is good - if they were, that would probably have meant you were leaving money on the table.
Then you say 'okay, what sort of figure were you thinking of?' Now you're negotiating.
I'd say the above becomes more true the bigger the company gets... Small companies <10 employees this theory could well breakdown.
Personally, I research what is a 'standard' pay in that geographical area and then add ~15%. Nothing to lose, a few thousands to win :)