IMO, the Axiom Pulse 60 taillight from Performance is the best sub $50 light you can buy. Very bright, wide beam, USB rechargeable. Mine has been fine in all weathers. On sale for $30 most of the time.
About $25 is the bottom end for decent taillights anyway, so the extra $5 is worth spending, especially if you have a Performance shop nearby that you need an excuse to go visit.
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Work: the 8 hours that separates bike rides.