I doubt that you'll be able to find a pre-painted Chargespeed kit anywhere. It's exceedingly rare for a distributor to paint the kits that they sell.
You'll probably have to just buy an unpainted kit and get it done at your favorite bodyshop. Make sure you have your paint code handy

 

You can find it either on the driver's side door sill or on one of the sides of the engine bay if I recall correctly... I'm not sure at the moment. Or you can just ask the dealership

Or... it may be best to run a search here on the boards for "paint code". It'll either bring to a thread with a list of codes or where to find the code. Good luck.

 

You can also go on paintscratch.com, if you remember the name of the paint they have a little chart that you can look at

For the 04' Imprezas:

Platinum Silver Metallic Clearcoat 01G
W R Blue Pearl Clearcoat 02C
Savanna Green Metallic Clearcoat 07V
Midnight Black Pri Metallic 08V
Graystone Metallic Clearcoat 09V
Sonic Yellow Clearcoat 13V
Java Black Metallic Clearcoat 18L
San Remo Red 22G
Pacifica Blue Metallic Clearcoat 23W
Steel Gray Metallic Clearcoat 26D
Woodland Green Pearl Metallic 29W
Pure or Aspen White 51E
Sedona Red Pearl Clearcoat 94H
Blue Ridge Pearl Metallic Clearcoat 95H

Two Tone Color Combination 2K1
San Remo Red 22G
Steel Gray Metallic Clearcoat 26D

Two Tone Color Combination 2L6
Pure or Aspen White 51E
Steel Gray Metallic Clearcoat 26D

This is straight from Paintscratch.com, i take no responsibility in saying that it is absolutely correct, check your engine bay =P