There are several high-powered LED headlamps made for 3W, 6V dynamo hub applications: Busch & Mueller IQ Cyo and IQ Fly lamps and the more expensive Schmidt Edelux and the Supernova E3.

As to other dynamo solutions, a wheel driven bottle generator or a bottom bracket generator, inexpensive 6 volt bottle generators can be had for about $50 (12-volt is another story, those are expensive). All-in, you could have a bottle generator and state-of-the-market high-powered LED for between $125 and $160, US. This is for a headlight to see by, not just to be seen with.