Interview Questions?!?

When being asked to give my salary expectations on an application, I know that I'm supposed to put down more than my actual expectations to leave room for negotiation. But how much more should I put? I mean of course I want the maximum possible but I don't want to put an amount that will totally disqualify me from the job since I would be fine with something that's not the maximum, you know what I mean? By the way, there's no room for me to put negotiable either, and just allows numbers fields.