WANTED frame and crankset for Fixed-gear build

Looking for a few things to build up a second bike after outgrowing my old Langster:

• second hand 54 frameset / anything that would fit a 5' 10 human. Ideally around £150-300 mark
  
• fancy-ish track crankset + chainring, thinking sram omnium / rotor 3D24 (FOUND)
  
  

Thinking of swapping the rest of the build over from the old bike and slowly upgrading, but someone has any other worthwhile parts, shout!

Cheers!