I would sell all my Bitcoins if they get to 550$-600$.
But that's what I say every single time when I'm waiting for the right price, they I always want some more but before that the price drops. That happened this time as well

At a moment $1000 would be the good price to sell bitcoins and make a profit out of it, but selling all bitcoins is not possible as we want to hold it for future too, as we are not aware that what would be price of bitcoins in next 10 years so selling part of it is always an better option So I would sell my part of bitcoins if the value reaches to $1000.