Unfortunately I went through an out of state new vehicle purchase that the Republic of California wouldn't let in back in 2006 because it didn't have that sticker, even though it was registered as a 2006 model witch was supposed to be 50 state CA legal. I wanted to make sure buying a SC outside of CA had ALL the legal and emissions boxes checked.
Now we need someone to go through and outline the exact process to buy an SC in Canada and register it in CA. I wasn't willing to attempt it myself.
WHAT ACTUALLY HAPPEN BACK IN 2006:
I researched the 2006 MB Sprinter Van as a first year they were a 50 state CA legal model. I bought a van conversion on eBay at a HUGE discount in Colorado with a 2006 model year and registration, but it didn't have the CA legal sticker on it. Come to find out, because of the time it takes to convert the van, the chassis used was a 2005 (with 2005 engine) even though it was registered as a 2006 vehicle. CA said it had to go back to CO for a full refund, because the dealer knows they couldn't sell that van to me legally as a CA resident. The dealer tried to skate the law by registering it as a used vehicle, because it had about 1,500 miles on it from using it as a show vehicle at events. But CA doesn't recognize a vehicle to be used unless it has over 7,500 miles on it just to stop illegal vehicles from being bought out of state and brought in as used with low miles. If it actually had 7,500+ miles on it CA would have let it in.
To further complicate the title of that particular vehicle, CA flags the title as an attempt at illegal entry into CA. Thus that particular vehicle can NEVER be registered in California EVER! I pity the person that buys it down the line with over 7,500 miles on it thinking he can register it in CA. He's going to be in for a huge surprise.