I'm not sure they're any cheaper than the "aftermarket" CDIs listed for the 400EX. I just checked DGY and they sell the XR250 CDI for $100. And they are considerably cheaper than most OEM part stores. You can get the AMR Stage 3 CDI for like $80 on eBay. I still don't believe CDIs are worth the money, anyways.
'05 TRX400EX:
|White Bros. E-Series Exhaust|Sparks +6° Key|42mm Keihin Carb: 165 Main, 52 Pilot|ESR Airbox Eliminator Kit|TAG T2 Bars|MSR AOF Clutch Perch & Lever|Burgard +2 A-Arms|G-Force Extended Hubs|KFX 450R Shocks|IMS-Roll Classic Bumper|AC Racing Blackline Pro-Peg Nerfs|ITP Holeshot H-Ds|Skat~Trak Extreme Paddles|