Batteries/Dynamo - each have their place.

For forgetful me, the led/dynamo setup is king. It is always there, never needs batteries or bulbs. I forget to take lights, to take them off, to replace batteries and to recharge them - hence why I like my dynamo so much.

If I were downhill racing in the middle of nowhere at night, then batteries would probably be better.

As to cost. I needed to have my front wheel re-built anyway, so it made sense to do it at the same time as I wanted a hub and have non-standard wheels.

I bought the Shimano DH-S501 32 hole disc brake hub in black from Rose Versand - current price is £56.37 GBP + £7.60 GBP P&P
I bought 40 DT Swiss Champion 2mm x 174mm spokes and nipples in black from Taylor-Wheels for €37.95 EUR + €9.99 EUR P&P
I bought my lights second hand from ebay, but the equivalent lights from Rose Versand cost
- B + M Lumotec IQ Cyo RT Senso Plus 40 lux (black) - £60.66 GBP
- B + M Toplight Flat S Plus (standard) - £11.19 GBP
The wheel build cost £20.00 GBP at my LBS

Total cost, £176.39 GBP (approx €208.50 EUR or $275.50 USD)

So yes, high initial outlay. But worth it for the hassle free, always there, lighting.