I bought a set of these (branded Polaris) on the high street recently for £30 and thought I'd get some for my kids too. Checking out the Net I found Wiggle selling them for £17.99 the set, half the usual price, and £7 cheaper than the 3-LED set in the same range. They're powerful, well-made and street legal, and the set I bought included good batteries.
A good buy now the days are getting shorter. Wiggle offer free 2-3 day delivery and if you spend over £50 you get 10% discount automatically.