The turn signal lens of my JD1025 was broken (while my wife was cutting grass, she admitted it.). While buying a drive belt for a mower, which the JD dealer had in stock, I inquired about ordering a replacement lens. A few computer strokes later, and the parts guy said "I have one in stock". $19. Yes, expensive for a lens, which probably cost $1 to make. But, it was bagged, tagged, inventoried, boxed, shipped to my local dealer, who had the foresight to think my wife might break one, and he held it in inventory at his cost for who knows how long, until I came along. Along the way, its value increased $18. Was that reasonable? Well if minimum wage is $15/hour, and an hour's total time was spent documenting it, and getting it there, to wait for me, let alone the cost to hold in inventory, I can't complain much.
On the other hand, has anyone gone to purchase the sets of shouts for the end of a vacuum cleaner hose!?! The set of four snouts is usually $20. They must make millions of them, and every hardware store stocks them without a thought. Yet, were they to be pink, and a child's toy, we'd think $1 was the right price for them!
When I think of the hours I have spent searching for a part I need, or more hours I have spent making it, if I can find it for purchase, even costly, it's usually less costly than my time to "go around" buying the proper part!