Reminder please, "Be kind. Don't be snarky" (source: https://news.ycombinator.com/newsguidelines.html )

She shared her motivation, which was a simple project to get into electronics to sate her curiosity. And as she concluded, had fun and learnt something new. And as a cherry on top, reduced the amount of waste that went to a landfill, bravo.

Something for all of us to aspire by.

I would say $15 is cheap for the learning, growth and experience. Interacted with humans too along the way. People pay much more than this for schooling which teaches you less.

So what?

I replaced a lezyne light battery too. There was no point buying a complete light, send this one to waste when I could just look up for the actual reference in a search engine, find the correct one and replace it.

It is not about money, it ia about not sending unneeded stuff to waste management, which we pay for actually.