why would you come up with some to-the-$1,000 asking price in a salary negotiation rather than just asking for 30% more than you'd be okay with?
i know he has another version where at some point in the negotiation (rather than the beginning), you whip out some very precise number, but that would immediately strike me as a psychological play rather than the honesty/thoughtfulness it's designed to convey.
in a different situation it's certainly more effective, like when requesting a budget/expense for a specific project, since it signals you've done the math and not just throwing inflated approximations.