The only DDR 2100CL2 I have found is Corsair, but only in 128M modules because the 256M was recently recalled. This is based on some thorough researching I have done over the last week.
I prefer 256M and CL2 myself. Then again, it appears all the CL2.5 DDR from Corsair, Micron/Crucial, and Mushchin appears to work well - stable and capable of decent overclocking. This is what is being said out there, no first hand experience.
Please, if anyone wants to expand.