Got a link to that detector? The cheapest self-contained lightning sensor in a portable form factor I know of nowadays is the Acurite 02020 and it's around ~$50 nowadays.

That's interesting. That's the same one I have, but I only paid $27.99 for it. I couldn't remember what the model was, but Amazon shows that I purchased that model and clicking the View Order link it shows $27.99. I guess I bought at the right time??? Maybe it's tariffed to death?