I've had a couple from poundland I thought they worked well... however it was let let down by build quality and letting water in on wet commutes... couldn't cover in it in cling film or a money bag (usual trick for wet weather) as it stopped the lasers from being clear on the road...
If someone copied the design in alloy and made it waterproof... and perhaps a tad brighter at say £30 they would have a winning product