Assuming it's something I want / need - I take what I can afford.
Some things have to be all or nothing. Others things are a take what you can get and be happy for that.
If I have what I need, I'm usually happy! Let someone else haggle over the rest.
I'm not sure. I guess it depends on what I'm taking.
If I can get what I want about 80% of the time, I figure I'm doing rather well...