One set of used SBK forks from eBay - Around £80 upwards.
  One set of 53 mm clipons - £100 for raised RobbyMoto ones from Busters. 
 Either have your top yoke bored out from 50 mm to 53 mm (which although cutting it a bit fine IMO seems to be common practice in the US) or buy a Cyclecat top yoke from the States, Spareshack or Nelly for $325. 
 Fiddle around with fitment a little bit and finally end up with this.... 
  If you want more precise details of whats involved U2U me your email and I'll send you a copy of the detailed mail Scott Brunt (The guy that owns the bike above) sent me about whats involved.