Decline
Bid distance, but decline outright when already carrying out a task.
Included because declining has to be demonstrably ordinary. A rule that always returns a number makes "no" indistinguishable from "very expensive", and the first time a modeller wants a vehicle to genuinely refuse -- a fault, a flat battery, a shift ending -- they will reach for a large constant and discover that a large constant still wins an auction nobody else entered.