I have been quite satisfied ordering batteries and chargers from PSS Enterprises in Montreal.
I use the Maha 2100mAh 4-Pack AA IMEDION Ultra Low Discharge Batteries to power my flashlights, headlamps and GPS units. (PaulsFinest.com Link)
It is quite important to avoid the classic NiMH batteries as they show poor performance in cold temperatures and discharge extremely quickly while sitting in your pack waiting. “Low Discharge” or “LSD” NiMH batteries are a much better investment in my experience.