Unfortunately it's not as simple as simply connecting the dynamo wire to a battery to charge it. They make equipment that will let you charge a light (is the light charges off of usb, if not it won't work), but that's more expensive than simply buying any dynamo light.

I'm confused - you post a link to a $67 light, then ask for a dynamo light that's $30-$40?

As the previous poster suggested, the B&M Lumotec IQ Fly N ($30 from Peter White) is probably your best bet at that price range. But don't expect much from it - I expect the other poster will disagree, when I used a light that dim I found it unacceptably dim and (imo) worthless.

For $50, you can get a Lumotec Lyt, but it looks pretty weak -


For $70 (similar to the actual cost of the light you posted a link to above), you can buy a Lumotec Cyo - it's what I've been using on my bike for the last 2 years. It's a solid light, because of it's excellent beam pattern, the only battery light that I found that actually beat it in my preference for riding was putting 2 Light and Motion lights on my bike, which was very expensive and...well, etc etc. You might also be able to find used Cyo's, now that the Cyo Premium is out.



For $110, you can get a Lumotec Cyo Premium which is similar to this -


I have the battery version, here's my own pic -


I don't know how much you plan on using this light and bike. In my personal opinion, the Cyo costs the same as the MiNewt you mentioned above and it's a decent light. The Cyo Premium costs more, but it's worth it (for me).