The question isn't how long it was driven after the bolt fell out, but how long was it loose, with the harmonic dampener wobbling it's way forward, creating an unbalanced state on the front of the crank, which more than likely caused some very nasty vibrations along the crankshaft. Probably does need a new crank, all new bearings, and a new dampener. How's the front timing cover? Got any grooves cut all teh way thru from the dampener? Have to pull the motor, strip the bottom and front, check everything to verify that none of the rods and main journals in the block are damaged. This is an extensive job. Figure 700 for the crank, 400(guess) for a new dampener, 100(again, guess) for new bearings, extra 200 for timing belt, water pump, new coolant, oil, oil filter, gaskets, etc., leaves 800 for labor. Seems about right with all new parts.
This isn't just pull the crank, slap new one in and done...