No, you're missing the point. For one, DIY projects are great for learning. Secondly, unless you already have a way to earn money with that time, time spent on stuff like this is "worth" $0. You'd actually have more money in your pocket after DIY'ing it and spending a couple hours than you would clicking "buy" on Amazon.com and spending a couple minutes or so.
And, if you want to get really nitpicky, I'm pretty sure all those parts the author bought were also tested and warrantied by their respective manufacturers. And, show me a camera warranty that would be broken by using an adapter that's made for the card type the camera takes, anyway.
SMH.
50 weeks per year at 40 hours each is normal, so rule of thumb: hourly rate * 2000 hours per year = yearly earnings.
The warranty aspect is a great point though, if a commercial photographer did this and lost their client's work because e.g. the pins broke off, I fear their clients' response.
The answer here comes down to what the individual is able to justify to themselves, be it via a cost-benefit analysis or merely "I'm a solo/hobbyist photographer, I could build this tomorrow evening during downtime and save some money, let's do it." :-)
I still am totally in line with my sister comments in valuing the fun building something and understanding a few things a bit better in the process quite higher than the economic aspect. This would only be the icing on the cake.
The author links to (approx) $90 in parts.
Your average HN reader is probably in a decently paid job, let's say it works out to $80-$100 per hour (at least !).
So we're now talking about $190 all-in, i.e. parts AND labour.
So we're now talking about a $60 price difference ($250 off-the-shelf vs $190 DIY).
For the $60 difference you get:
I'd say that $60 is a bargain.People should not be valuing their time at zero when engaging in DIY projects.