Extra rows or Quantity Column DB Design
Your table structure is defined by the entity model it represents, not by opinions.  

If components need to be represented individually, e.g. if they have unique serial numbers, different prices, or arrive as separate shipments, this would warrant separate records for each. If components are indistinguishable from each other (cf. nails, bricks, or gallons of paint) there is no reason nor method to track each one separately.