We run a 2001 Century with a 2000 engine. CARB requirements are a particulate filter upgrade at this time. I picked at random one of the "recommended sources" from their website and sent an email asking for a rough price quote for the upgrade. The dealer quoted over $16K for the kit, not including installation. Tough to justify that much expenditure for even a dozen loads a month on a truck our age.
Our reefer did age out last year (it was a 2004), and even our original APU was too old. The reefer was more trouble than it was worth, since I never could qualify for TVAL with FDCC, and the APU died with a little help from a service shop that obviously didn't know what they were doing with it, so the reefer is gone and the APU was replaced. That still leaves me with a 2000 non-compliant engine, though.
CARB offers a 1-year extension of eligibility through 12/31/13, but you MUST register with the CARB system by 01/31/13 to qualify for it. If you do this, be sure and print out the certificate they offer so that you can show you are registered if you get pulled over in CA. They are checking, I'm told. Registration can be done online at arb.ca.gov/truckstop . You will need, among other pieces of information, something called the "engine family." This info should be available on one of the stickers on your engine, otherwise you'll have to call the manufacturer to get it. CARB says it takes 15 minutes to register, but that's after 4 or 5 hours of tracking down all the info and getting clarification of what exactly they want on their forms (based on experience). Call volume to their help line is heavy and they are warning of delays of up to a week for return calls to messages. If you need or want to apply for the extension, you need to get on it right away. The clock is ticking.
Getting registered lets me continue to take loads to CA for this calendar year, but after that, unless my income is up substantially after changing to Landstar, I'll be ripping several pages out of my road atlas. I can't afford to replace the truck when I'm getting the same or less than I made when I started but the new truck costs nearly double what I originally paid.