Just purchased a circa 1953 K-38 at a gun store in the Palm Springs area of Southern California. I was able to get it and he was able to sell it only because he didn't own it. ONLY guns on the California Approved List can be sold OR imported into California. This gun was registered as a PPT, private party transfer, so the sale was legal. There is a relic and curio exception, as stated above, that guns over 50 years old can be sold as such and I guess this one could have been transferred that way? Not 100% certain about this.
Here in So Cal, when you find it, you better grab it quick. I got very lucky in that the owner of the store and I hit it off with mutual friends and hobbies and he cut the price considerably. He also had only recently got it for sale. Picked it up for $350, all original including matching numbers everywhere stocks included. I wasn't even gun shopping, just killing time while the wife was at the mall.
In summary, here, when you see it in a store, it will be a consigned gun or the dealer can't sell it. Effectively, it is the same transaction as if I knew someone who had one......we can just may a deal and walk away, we are required to transfer it via a dealer (PPT) or we are breaking the law. Great huh?