I don't know exactly what you're looking to get done, but you might try to nail 'em down on a price. $80 an hour does seem to be at the high end of the scale, but if they've been at it long enough they ought to have some idea of how long it will take. That way if it takes 'em longer ( too many coffee breaks, too much time looking at it hoping it will do itself, etc.), at least you know your cost up front. Can work both ways though.....might take 'em half as long as the estimated.