Where can I buy it and what should I buy.
A long time ago the XML trustfire drop in from manafont was one of the best and cheapest. Is that still the case?
And is there any reason i should go for a xpg drop in?
Thanks
Best is relative to your requirements. It's not the cheapest by far, but I really like mine. My only complaint is the visible PWM at low and medium.
"Best"? Nailbender, but you are going to spend a lot of money. Also Malkoff or Thrunite, but again, you are not in the budget zone.
I have really never looked into the Nailbenders but what makes them so good? Im making my own dropins these days and am always looking for ways to improve the product. Right now I use great drivers and pot the electronics. I tried searching the Nailbender but only have the rest of my life to find a build thread and Im already old. Anyone have a link to a thread showing the construction of these famous dropins?
For me it is the ultrfire 3 mode T6 p60 drop in.
I have a nailbender XML drop-in that I got a year ago. Its great, but honestly I was more of a n00b back then and I wouldn't have bought it for the price knowing what I do now.
I have 3 of the Manifont (Ultrafire) P60 3 mode XM-L's and I'm quite pleased with them. Super bright and reliable so far..
It wasn't the cheapest, but the best one was/is Ultrafire 3-mode from MF (not Trustfire).
As for XP-G... smaller emitter - better throw. XM-L has too bright spill, XP-G has slightly brighter hotspot with less spill. So, it depends on what type of beam you need.
Keep in mind, I still like my old XR-E R2 as well... 1/3 the power, and better throw than the XM-L. If you don't care about the narrow beam angle...
The MF XM-L is my current favorite though... Just get some good cells to go with it or you will never realize its full potential! 
P-60 modules need extra care for heat sinking, due to the design.
A member here creates top quality dropins...
https://budgetlightforum.com/t/-/2707?page=2#comment-104167
The point is that his drop-ins are better than Nail-Painter...opps Nail Bender.... and perform better.
Read up about it.
Don't forget the lower current draw resulting in increased runtime. I'm all for the XP-G for this reason! (Note, I don't own a single P60 light. I know, I know, I need to get with the program and get one!)
-Garry
Yes but here we go again: what are good cells..
Right now i have some trustfires (2 protected and 2 unprotected), 4 xtar 2600's and 6 sanyo unprotected on the way for use in my ordered DRY.
I heard those panasonic's from outdoor aren't to bad either but it seems the protected ones aren't available anymore and weren't so good (cut off at to low amps). They do also seem to have unprotecteds
Then i also heard all this talk about imr's and so on but i don't know where to get those 
Besides are unprotected so bad? Normally if you recharge them everytime you went out for a walk it couldn't hurt right?
Yes sir ;)
And KDLST, those XTAR you have are excellent, and those Sanyo too. I have TF black and no prob with them, but XTAR and Sanyo are better.
I have used a generic P60 XM-L from Kai or Ultrafire from Manafont as base and changed driver for 1,4A -> 2,8A 3-mode High PWM ones.
Too bad there are no dropins available with high PWM circuits :(
The best drop in for the money is the Manafont 3 mode XML, I have purchased a half dozen of these for myself.
Of course if you want a regulated drop in with no PWN and custom modes I make an identical one to the "nailbender" for significantly less money and with many more options.
I have the Manafont Ultrafire XML 3 mode drop in myself.
Here is what I did:
Wrap the drop in with fine copper wire until it has to be pushed in....as it goes, use a butane torch to melt silver (real AG) solder all over it....then push it in while it is still soft.
That's a great way to bed the pill into a light for maximum heat transfer. Thanks for the tip I will give it a try.
like erik said, for the money the mf uf drop-in is the best, for sure. it is competitive with anything available, but for a lot less money. you can get better, erik builds them for not that much, and there are other custom builders on the hated forum. the brightest i own, by a pretty good margin, is a one-mode custom built. it just depends what you want. i think erik (E1320) will be one of the best to consider, as he now does some custom mode programming.
the warm whites aren't as bright overall, but wow, they look great. i hope that as everything progresses, there will be some brighter warm white drop-ins available.
I built myself some XML dropins lately. I used a 3-18V driver found on DX for $2, a XM-L T5 emitter I once found cheaply and a SMO reflector I guess I found from DX. I thought a SMO could focus XML better but the beam was really ugly although the reflector was a really perfectly clean one. I then switched the reflector with some other OP reflector, hopefully the one I thought I got from DX for $3 and wow, the beam was much better focused, and more like a midrange worklight now. Perfectly smooth spill as well.
Now I got a >450lm bright, one mode drop-in that I put into a 2x18650 extended SF L2, draining only 0.7 A on the tail. A near 4 hours runtime for such a bright one mode light is more than perfect for me. Not just because I did it :)