does it leak where the cap is or is the metal on the radiator actually cracked? if its where the cap is you may only need a new cap

If you do actually need a new radiator itself I would look at the mishimoto radiator. S&R Performance is actually a dealer for mishimoto so they can get it locally for you. Import Image Racing Webstore - SUBARU - WRX/STi 2002-2007 - Engine - Cooling/Hoses/Belts - Mishimoto 02-07 Subaru WRX/STI Radiator