SilverShop\Model\Modifiers\OrderModifier::Amount
This function is always called to determine the amount this modifier needs to charge or deduct.
If the modifier exists in the DB, in which case it already exists for a given order, we just return the Amount data field from the DB. This is for existing orders. If this is a new order, and the modifier doesn't exist in the DB ($this->ID is 0), so we return the amount from $this->LiveAmount() which is a calculation based on the order and it's items.
Signature
public function Amount()