There are a ton of options here, many are crappy knock-offs with fantasy power ratings... Name-brand prices are sky high.
I strongly prefer the red foil-wrapped Trustfire batteries, and DX has them at great prices. DX tests capacity, and if it is overstated by the MFR, it will be "in quotes" with the tested capacity listed in the description.
The Trustfire's are considered "protected" cells, since they include a circuit board that protects them from under voltage and short circuit issues that can create fires. Ultrafire's suck, stay away! My favorite, made by Trustfire:
Trustfire 18650 (dia. 18mm, len. 650mm) -. 2/$10
There are a zillion lithium charger options out there, starting at $4... If you buy a cheapo, I suggest only using protected cells to reduce fire hazards...
Considering fire safety and overall convenience, I finally settled on the SYSMAX Intellicharge i4 JETBeam Nitecore Li-ion / NiMH Battery Charger V.2 $27:
The Sysmax is a great charger, charges everything (Lithium, NiMH, and NICD), in any combination, automatically, using the preferred method for each cell type. Super safe and super handy, even has a car adapter... No other charger currently supports all three chemistry systems, since some require constant current and the other constant voltage.
NOTE: DX items are made in and shipped for free from China. This takes about two weeks, so prepare to be patient.