Sounds like these are made to customer order, if so then the cost is Cost of Sales and not Cost of Goods Sold. COGS is directly related to the cost of the items you stock for sale when you file income taxes so it is best not to get them mixed up.
Create a COGS type account named cost of sales in the chart of accounts and use that for the purchase of each included part.
But no, one item one account is the way it works