GearBest offers the Nitecore Tube LED Keychain Light in Black, Blue, or Transparent for $9.99. Coupon code "NTdeal" cuts it to $5.99. With free shipping, that's tied with last month's mention and the lowest price we could find by $4. It features up to 45 lumens, rechargeable battery with up to 48 hours of run time, and two brightness levels.
Note: This item ships from China and may take two to five weeks to arrive.