Ebay is your friend and you can find there LED bulbs that you can use in place of incandescent bulbs in lamps, with quite a bit of flexibility in the characteristics of the power source:

Nicelite LED Bulbs Dynamo Hub Generator Dynohub Bicycle Cycle Lights Regulator | eBay

You can find many more on German Ebay, but you presumably need to negotiate a shipment abroad:

fahrrad birne led | eBay

You are likely to get more improvement in the rear than in the front.