CygoLite Hotshot Micro - This has far more side visibility than the Hotshot. Smaller and lighter. What I like is there's two modes I can use for group riding. (Nothing more irritating than riding behind a bright flashing red light!) The only thing I don't like about it is that the cover for the USB port comes off too easily. They should have made the cover longer so it would fit further into the port.

And yes you can find these lights for less than $25 w/shipping on ebay.

CygoLite Hotshot Micro