I agree, I'm not the most representative of HN users, so I can't gauge how willing one of them might be to pay the higher price. Maybe someone making six figures in the US (the average user on here?) wouldn't mind it, but I imagine that if we look at all techy people and not just HN, things would be closer to the mean.

For me, a $100 purchase is something I can probably justify if I think I'll enjoy it a lot. $250 is still a 2.5x upcharge, and I consider these expenditures for a long time, making sure that I really actually need it.

And then, the $100 is just an example reference. It's sold by Adafruit, whose selling point is trading some value in exchange for reliability, convenience and compatibility. When you look at the market in general, I can find countless cheap pre-built Geiger counters at prices that are a lot closer to $50. I can't vouch for their accuracy, but there are so many unique options that I imagine that at least a few will be pretty decent.