I've used Amazon and eBay. Magicshine lighting systems are really bright, but you have to make certain that that you have room to mount the light head and switch assembly. I've modified a water bottle to hold the battery - into the downtube cage or below-downtube cage (tourer).

Sending you links won't help. You have to decide where you will mount, how you will recharge, and your budget. For me, the flashlight with rechargeable battery route doesn't sound attractive. I'd much prefer a Lumina 650 or 700 with the helmet mount, plus another one for the handlebar. Battery is internal, package is water tight already. Micro USB charger, available at work or at home, compatible with smart phone chargers I already have. All of that.

The MagicShine triple head is really versatile, but it's not for everyone. I like it. You need to buy backup battery packs if you plan to ride more than a couple of hours at full power, though. So, there's a weight penalty. They velcro to the frame, so storing/carrying isn't a proble.

Anyway, I'd recommend that you design your own lighting system to meet your own needs. There are no shortcuts to doing this right.