Low-cost LED caps for repurposing nearly-dead 9V batteries

A user mentioned, "I wanted to get some of these..." and expressed a desire to use 9V batteries from smoke detectors that "weren't quite dead" for lighting around the house. Another commenter pointed out that a similar existing product is too pricey ("It's like 20 bucks"), but they might consider it for "$10." This shows there's a need for a very low-cost solution.

Product Suggestion: An ultra-low-cost, minimalist LED light attachment for 9V batteries.

• Design: Extremely simple, with one or a few small LEDs, a current-limiting resistor (if needed), and a standard 9V battery snap connector. The casing could be a very small, basic plastic enclosure or even just heat-shrink tubing over the soldered components to keep costs minimal.
• Target Price: Significantly below existing options, aiming for a retail price in the $1-$3 range per unit, or offered in multi-packs (e.g., 3 for $5, 5 for $7) to encourage purchase for multiple repurposing uses.
• Function: To provide basic, low-intensity illumination suitable for small tasks, as a simple night light, or for finding things in a dark space, specifically designed to get residual use out of 9V batteries that are no longer potent enough for their primary device (like smoke detectors).

Expected Benefit: This product would serve a niche market of frugal and environmentally-conscious consumers looking for practical ways to maximize battery life and reduce waste. By addressing the specific pain point of existing similar products being too expensive for such a simple repurposing task, this ultra-low-cost alternative has the potential for high-volume sales. It could be an attractive impulse buy or a practical utility item, particularly for using up partially depleted 9V batteries that would otherwise be discarded.