Crazy right? Typically (if you aggregate the reviews) the differences are build quality and maybe battery quality. The build quality on the 4 that I own is very similar to the magic shine original, and while I have read some stories of spotty battery life, I haven't experienced it yet. The original magic shine button lights up different colors depending on the battery status (green, then blue, yellow and red) whereas the faux models I own do not - so buy two and carry the spare, they're not heavy. The battery connection is also more water proof on the original but we live in So Cal, so who cares.

The cygolite models listed above look like they might be more secure on the handlebars, and you can just whip 'em off for recharging, so that might be more convenient. The magic shine version (and clone) attach with a big rubber band thing, so they can wander around on your bars a bit in terms of where they're pointing.

$20 though... hard to go wrong.