Fixed gear kind of mountain bike

Hi, while scrolling through the photos of the beater's topic, I fell in love with this bike. I have always to build myself a double disk fixed gear bike, then it became more of a singlespeed mountain bike but this is exactly the spirit of what I want. The main thing is I need it to be as cheap as possible.

The thing is I have no idea where to start:

• Do I build it out of FGFS frame as it has horizontal dropouts, and as it can receive wide tires and a BMX crankset?
  
• Do I build it out of a track frame with MTB forks but that means finding a recent frame that can receive 1"1/8 forks to get a beefy look and a BMX crankset but that can't get wide tires?
  
• Do I build it out of an old MTB frame which means both welding and finding horizontal dropouts?
  
  

I really know what I want and don't want to make compromise! I need it to be ratty, have a BMX crankset, 1"1/8 forks, compact geometry, 26" fixed wheels with wide tires. I just have no idea what my best chance is concerning the frame I start with.

Thanks for your time and help.

Simon

1 Attachment