I'll agree that buying too cheap of a light is a mistake. I've spent more on ****ty lights than I have on good ones, over the years. It's best to go ahead and buy something good the first time. I think the MagicShine is a good deal, providing that you can treat it gently. It doesn't have to be coddled, but the battery isn't waterproof and you can't abuse the wiring or it'll fray. I know people who beat the crap out of everything they own and then complain that it's garbage when it breaks. If this is you, look at Lupine for 6 times the price for essentially the same thing; it'll stand up to more abuse. But if you're OK with treating things like an investment, the MS is good value.
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Work: the 8 hours that separates bike rides.