You said cheap so I am going to recommend this one.
Mine has worked without any issues for 10 different dives over a 6 month period.
There seem to be several "brands" of it and they look to all be knock offs of each other, or they all came out of the same factory.
At the price they are selling they are almost disposable. Use it for one dive trip of several dives. If it lasts a few more dive trips you've gotten your money's worth. Keep in mind the light is not that bright and can illuminate small holes in the reef, etc. I even used it as a primary during a night dive, but I had a much stronger light as a backup.