I've probably spent $250 on rear blinkies over the years.
They all had fatal flaws.
Either they had weak mounts, weren't bright enough, or would spontaneously shut themselves off

I just passed 1 year (longest any blinkie lasted) on my current one, and the funny thing is, it's the cheapest of the bunch - a 'Raleigh'' purchased for $12CA from the bike section of Canadian Tire..