Good rear bike light £10-£20 (is that enough?)

[Angelfishsolo]

As above, I recommend Smart Superflash, the new Smart 1 watt, Mars 3.0, Mars 4.0, RSP Astrum (2 x 1/2 Watt LED), Nightrider cherrybomb, to name a few that are about £20.

Look to have two lights minimum though - 1 backup.

+1 for the Smart. I have not had issues with water getting into mine either.

 

[fossyant]

+1 for the Smart. I have not had issues with water getting into mine either.

We've got about 5 Smart super flashes in the house - mainly from a silly sale that PBK has - £3 each or something. - That kitted out everyone's bike for next to nothing. Had trouble with two of the smarts, my original one, and the one on my sons bike.

Used two on my rucksack, which didn't let water in, but I'm now use panniers so they are on the missus bike etc.