Yeah I bought a ravemen 1600 last year to try out an all in one when one of my old external batteries died and even in the 40s the temp does a number on battery life. I just started throwing it in my pocket to keep it out of the wind till I needed it and running it on high pretty much all the time. In the colder temps low/med/high didn't really matter for run time. Run it on low and it its too cold and kills the battery, run it on high and it at least keeps itself warm and gets a bit better run time than bouncing between high and low a lot. I just bought a new external battery and keep the ravemen as a spare. My helmet light's battery sits in my backpack and my handle bar light's battery sits in the frame blocking most of the wind. I bought my new battery off kaidomain and they have a bunch of the standard cheapo chinese lights, shipped one for free with my battery. They aren't fancy but I started off 15 years or so ago with 2 of the super cheap $20 light and battery XM-L2 type they sell and 1 still works, batteries are both dead though. If you just want a cheap good enough setup pick two lights off their site like the solar storm x2 for $20 a pop and then get two of their batteries that are marked high quality that come with NCR18650B panisonic batteries. The cheap lights don't have the greatest beam patterns and they like to exaggerate their lumens but they do work. The cheapo batteries are really hit or miss so spend the extra couple bucks for the panisonic based ones. Or you can head over to mtbr's like somebody else mentioned and check out their "light and night riding" which has a huge "current bike light deals" thread.

I'd recommend my lights but they are both out of production. The xm-l2 is what they shipped for free with the panisonic battery I ordered if you want to go super cheap just get two of those batteries and hope it comes with the lights .