There are two basic kinds of bike lights:
1. To see.
2. To be seen.

The light from a "to see" bike light, including the strobe setting, is much brighter than the light from a "to be seen" bike light.

The "to be seen" type of lights are priced usually under US$20. These are the kinds of lights sold at K-Mart, Target, Walmart, etc.

For the USB rechargeable lights with several hundred lumen output, prices are much higher and are found at the local bike shops, and of course, on-line.

All lights are not created equal.

Ray