I used to buy those reflective ankle bands at cycling shops so my pants wouldn't end up caught in my chainring when I ride.
They run around $3-$5 a piece, and I'm sure I've run through at least $30 worth of them over the past four years. After I lost the last one I bought, I got tired of every loss involving a trip to a cycling shop and a $5 expenditure.
Solution? Rubber bands.
They're smaller, less likely to fall out of pockets, and when lost involve only forcing oneself to endure another portion of organic broccoli. I'll try not to lose them too often intentionally as a result.