just look around at all the popular US airsoft sites. they all have em and they are all about the same price...
also caution get the Version 1.... the version 2 comes with the long mag BUT version 2 also comes with an outer barrel that is NOT threaded at the end so no add-on's (if you know what i mean)
Buy Version 1 with the stubby Mag.
then buy either Green Gas long mags or CO2 long mags they have both available...
Remember to make the KC02 a contender you need to at a minimum
a. replace the Hop up rubber (RA Tech or Falcon work great)
b. replace the Inner Barrel (either the RA Tech 380mm 6.01, RA Tech 510mm 6.01***, or Falcon 510mm 6.01
*** if you go 510mm you will need either the Falcon barrel extenson (about $50 if you order direct from Falcon) or $79 from everyone else (if in stock) or something on the end of your barrel to house the inner...