Some vendors will sell in Kaliforgnia.
Venice is just one.
Custom Motorized Bicycles / Bicycle Engine Kits / Los Angeles| VeniceMotorBikes.com
Here's all you need to know about the laws:
bairdco's first post in the thread says all there is to say. All the other posts are good to read but are mostly discussion.
"It's a chinagirl. It's a sometimes fun little engine that often will break your heart. It's disposable.
Does not come with a fortune cookie."