Since you need a new system, there is the USB2BYK: Website in French
http://eurecart.free.fr/
and to order:

I just ordered one and will get it soon but it has very good reviews on french forums.
I bought additionally the battery (AAA) charger which regulates the current, allows to use the light even when we stop and allows to charge the battery for my headlight.

For a total of 45 euros (<$60) I'll get the device shiped to the us.
That may be worth using google translate !