You see, I consider £70 to be expensive for bike lights...
I suppose in real terms, compared to income, allowing for inflation etc, they are actually cheaper than those enormous metal ones, with 4 x U2 batteries, that we used to use years ago!
Well, another possibility in the cheap end of expensive is
http://www.brightbikelights.com/
I have the Magicshine MJ-808 set (£90).
Very well built and terrifyingly bright at full power - I use it at a lower power setting in town.
It has also survived a full winter of commuting and a lot of use as a headlamp when running (on foot) off road.