Counting the capital cost of the inventory in transit is not a way I'd sure to determine it, as the inventory is not counted to the purchasers book in most cases until its received, not when it enters transit.
That said, there are many other reasons why apple wouldn't want to ship by sea, mostly the longer lead time to correct problems, and the potential for a large amount of defective inventory in the chain, not the mention the vagaries of market demand, and other factors.