About 10 minutes of really bright performance before it gets dim is what I've been hearing. Of course in reality it's doubtful that you would have it on for 10 minutes straight. More likely 20 second incidents, which would give you about 30ish clicks before you can really tell the pack is a lot dimmer.
This is based on reading not using, although I am building two of these. One with a 2D and another with a 3D mag.
With a soft-start switch
https://www.candlepowerforums.com/threads/177316 the run-time would be a lot more because you could use lower levels for utility and keep the shock and awe up your sleeve for those times when needed. Even on low with an AW soft start switch this light would really put out some healthy usable light (I'm guessing).
Prices for turnkey usually will be ballpark 300-400 bucks, some lower and some higher.
Keep your eye on the WTS thread in the Marketplace part of the forum
http://www.cpfmarketplace.com/mp/forumdisplay.php?f=123 . In fact I think there is a slightly ugly camo finish Torch like light there right now for a very low price (in the marketplace). At least there was a week ago when I was browsing. EDIT here it is
http://www.cpfmarketplace.com/mp/showthread.php?t=211884
Wicked Lasers sells a turnkey for about 300 but it's not going to be the same kind of quality that you will see here (so I hear, I know the battery packs look like crap)
If you make it yourself you can go cheap and get a direct drive one made for about half of the prices I mentioned, but would need to do some resistance mods to get the performance of the turnkeys.
Fivemega is selling some turnkey MaG 623 like lights that are styled a bit differently and with some unusual coloring you might like, click on the "my products Link on his signature.
https://www.candlepowerforums.com/threads/235766
This is a link of a closed sale, but it's useful for the links to FM's other products threads, check out Maxim 623
https://www.candlepowerforums.com/threads/228555 , Like I said they are different solutions than the ones in this thread, but they are basically supporting the same bulbs and doing it well.
You can also buy a bored host and just buy all the parts to put in it, and the bulb, you'd need a Batt Holder
https://www.candlepowerforums.com/threads/198633 , or better yet the brighter 13 cell pack
https://www.candlepowerforums.com/threads/191890 , a bored host, a modded mag switch(don't recommend) or a KUI kit(recommend) or an AW switch (really recommend, soft start 3 levels, and KUI holder is already mounted on it). You will also need a metal reflector and a real glass lens for the front, get a borofloat from glasslens.com (I think thats the name of the site).
FiveMega also has one more 2D prebored host in Gold for this build
https://www.candlepowerforums.com/threads/197038 , or you can have Jesus Hernandez make something for you
https://www.candlepowerforums.com/threads/156080 .
One thing to keep in mind is that some of us have the hosts but are unable to drive them because so few people have the capability to make a reliable high amperage 13 cell pack for the +1 version.
If you go longer in length you can use battery holders such as those the FM also sells as well as others and bored or unbored hosts depending on how long you go. The 3 wide ones fit into a D tube 3 times however D long your host is but you don't need to bore your light it just fits right in., the 4 wide ones you need to quad bore. For shorter lights with more voltage, like those in this thread you need to go with a pack, usually made with 2/3 A size batteries, and for those you need the tri bored 2D.
Hope this helps, I'd edit to make it clearer but it's time for me to jump in the shower and goto work!!
