Since cost is a factor, I'd go with batteries or maybe a bottle generator. If you are touring in May, June or July in Northern regions, you probably won't need to ride much in the dark. Battery powered lights would probably suffice for riding, and they could double as flashlights while camping. Maybe you could use a solar charger for your electronic gadgets.

For years I toured with a bottle generator with incadescent bulbs. Looking back, I wonder how. LEDs are so much better. The advantage the bottle generators have is that they have no drag when not in use. In midsummer that would be most of the time.

If you are planning to use the bike to commute or ride in the winter, a Schmidt dynamo hub would be a good long term investment.