because they can't make money selling one at a time.
DING DING DING.... That's your answer. They probably don't even make money on the bundled items.
I have a customer that calls me out for every little item that goes wrong on her property. Last one was for a tenant who "smelled smoke" in their office. Went out, she pointed to where the smoke smell was....right around the coffee maker and the microwave with a fresh bag of cooked popcorn. Of course I looked above the ceilings, everywhere, but knew the source.
Yep, charged them. Full hour plus trip charge, cust. didn't like it but they know I need to make money. The little things aren't free, someone always pays.
And, Yes, I would rather they not call me on these items, I don't make money on them but I am catering to their needs.
Sounds to me that's what WM and Raymarine are doing when they sell you the pins.
On a side note, doesn't sound like they are losing much business from you anyway. Buying items at garage sales and complaining that you can't get replacement parts cheap. Wow, they missed out on what you wanted to spend. $10. Ouch.
Here's a smiley face....