The pricing is fixed, there is a rate that works out either on the weight of the item or the cubed weight of the item, most times it will go on the cubed rate, this means that you will pay more for larger boxes, they will weigh the box first and then cube it, if the cubed weight is greater then that is what you will pay! Ask them to show you how they worked it out.
In terms of receiving goods it is not your responsibility, it is the responsibility of the person sending them and the office at which the item is sent from. AAE have an obligation to ensure that the animal is correctly packaged, if not the MUST refuse to accept it. Once the person at the desk signs for the animal, if it is not properly packaged they have accepted responsibility for it and if anything goes wrong it is on their head as they did not follow their own regulations. If you are shipping animals make sure it is done right and you avoid these hassles, I have received a large number of snakes of late, all have been properly packaged, no foam eskies, all boxes clearly labeled and crush resistant. The AAE do not need to ask if it is a python or venomous snake, the shipping of them is not handled in any different manner!