If you're looking for a somewhat cheap but still bright (~350 lumen) heres your answer...
Host: (a solarforce L2)
Solarforce L2 Host for 18650 Battery - Body with Head and Switch, all Black Type 2 Anodized
Light Engine: (Cree R5 based LC-XPG) This one is 5-mode (350lum, 210lum, 80lum, SOS, Strobe) you turn it off and back on quickly to cycle the modes, but there is a single mode also, and either one has a good tight beam, and throws a decent amount of light until about 65 yards away.
Solar Force LC-XPG Cree R5 5 Mode Drop-In
Batteries: I know this is a single 18650 host, but you need the voltage of
TWO 18350's.
AW IMR 18350 700mAh LiMN Rechargeable Lithium Battery
Another option is to use standard CR123A's or rechargable RCR123A's and wrap them in a bit of cardboard to make a spacer.
Charger: I hope this is self explanatory. This particular charger will work with any of the above mentioned batteries, and the light it will turn green when they are finished. That takes a lot of the guesswork out! Lithium batteries have a tendency to explode / catch on fire if under/overcharged. You can also test the batteries' voltage with a multimeter to see how much they are outputting, but each model of battery has a different range, just google it. A protected battery will cut off before your over/undercharge it, hence "protected", but they usually have a lower mAh rating (and therefore lower run-time) due to the need to squish the protective circuitry into the same size package.
DSD 2 Station Charger
I'm an aviator, and I use this exact setup for 99% of my applications. It works wonderfully, is relatively cheap and lighthound ships fast (they're located in TX). Another good company to check out is Oveready, but they are a little more expensive than lighthound.
Good Luck!
I'm really into building flashlights, so if you have any more questions feel free to PM me.