It's the getting it to the end user that costs. Much of the price of small parts is shipping, handling, and storage.
The fuel for the slow boat from Japan, the crew, the people who pack, load, and unload the pallets, and finally the rent or mortgage on the warehouse they keep it in until someone buys it.
Ever notice that the price of 1 liter and 2 liter soda is often within pennies of each other at the convenience stores, and sometimes the 2L is cheaper?
Costs more to transport/handle 2 ea. 1 liter bottles than 1 ea. 2 liter bottle.