Fellow commuters - is anyone using bar end lights?

I was looking at the little red lights that fit in place of the plug on your drop bars. I think the concept is that light at the furthest point makes you seem a little wider and helps encourage motorists to give another inch or two?

Has anyone any experience? The theory sounds good to me, but I couldn't find any of the big brands making them - only cheepies on ebay and that makes me think why? Perhaps they're not so effective.....

Cheers