I have a new (still in a box), Planet Bike blinky superflash LED rear light for $10 (half price). The package says it's the brightest, most visible bicycle tail light on the planet! It uses 2 standard AAA batteries (included) & gives you 3 mounting options ---- seat stay, seat post or belt/backpack clip. The mounts are quick release, so you can easily take the light with you when you park your bike. It has a unique flash pattern as well as a steady-on option.