STURME LED Safety Light Strobe Lights (3 or 4 pack with 5 extra batteries) $7.79

https://www.amazon.com/dp/B01N53854Z
40% off using promo code: 40Q94RGW
4-pack is $13.99 – $5.60 = $8.39
3-pack is $12.99 – $5.20 = $7.79
Shipping is free.