When I was checking into the airport this morning for my DUB flight, I received a notice that my JFK - ATL was overbooked and I was asked what amount I'd be willing to give up my seat for. I had no idea what to enter, but since we aren't in any rush (school/work commitments don't begin until Tuesday), I chose $400 for each of us. I just checked the standby list and the flight definitely appears to be overbooked for the number of seats available.

So my question is whether there is a guideline to follow for these kind of situations. Should I have entered less since it'll be a domestic flight? Any tips would be appreciated for next time!