What is the best single cell light for the $?

I am thinking the 300 lumen Arisaka is going to win for weight and maybe even the cheapest. I have no idea how they all compare for beam patterns or battery life. The 300 lm malkoff head has some range to it from what I have read while the CQB disperses it all up close

Need something for a truck gun that I can ID targets at 100 yards with.

From what I have understood, the Surefire or Arisaka with the E1 "thrower" head from Malkoff/Arisaka are your only two viable options. The Elzetta doesn't have any throw to speak of. I own an M300 300 lumen, and love it. I do not have any hands-on with the Malkoff. THe Malkoff is not reverse polarity safe, though, so if you get one, make sure you never fumble battery replacement.

ElZetta is hands down the best weapon light made today. I have sold almost all my Surefire lights and now use only Elzetta. They aren't cheap but quality seldom is.
NCH

Surefire patterns have a lot more accessories available to them.

Since I often run a white light with a PEQ or similar, its nice to have a tapeswitch option.

Thinking I may get the CQB to replace the Inforce on my house 870 and then I'll run the Arisaka on my truck AR.

I agree with that but the Alpha was not designed to throw out to 100 yards like the OP stated.   Surefire single cells will throw more FWIW

Elzetta for any serious use. Bar none

So Bright Flashlights put together and Arisaka scout light for $150 shipped. Should be here tomorrow. Also, exile machine had the IWC/Elzetta CQB for $150 so I ordered one of those to try as well.

I just received my Elzetta mini CQB. Love the light, hated the IWC mounting nuts that came with it. First the piece that fits under the rail is too thick and I had an issue getting it past the gas block before getting it snugged down more. Second, the nut would spin when I tightened the screw and the nut would not stay pointed in the forward direction without getting another tool to slide under the rail and push it back into place. I think the main reason for both of these issues is the nut is made for both keymod and Mlok depending on which side of the nut was facing the rail. For keymod the nut needs to be thinner and include guides so it slots correctly. I like the boot design IWC uses on their QD mounts.

Is Exile Machine legit?  They have some crazy low prices;  all black Raptor for $70, basic BAD safety for $45 along with many more really cheap prices.  

I have never had a problem ordering from them