I haven't seen Amazon's offerings, but they're likely similar to eBay's
I have one like this
, but haven't managed to get it mounted. The lights are fairly bright, and I like the idea of the integrated, automatic brake light, and there are a number of different audio horn sounds - not loud enough for cagers to notice, but good for pedestrians.
Overall, I'm not sure how much good this would do you in the day, but I'm interested in getting mine mounted. It'll be great for night cycling, if nothing else.