I'm not sure exactly what you mean. Are you saying that the business fares with Max bundle become $400 cheaper when the sale ends, or that you buy the sale fares then add the max bundle later?
Sorry, I meant that once a sale is over, the base fare increases but at the same time the max bundle cost decreases. They both must be purchased together at the same time to allow the fare to be refundable. So depending on the dates these non sale max fares can work out a little cheaper than in sale times. You may add a max bundle later but you lose the ability of the fare to be refundable, though the other perks remain.