If thats close to right a man could make a lot of money by buying guns in Oregon and selling them in Cali.
How hard is that to do legally?
Not too hard if you have a valid FFL.
Since, Kel-Tec is not on the CA DOJ BOF "approved" list, you can not legally buy a Kel-Tec from a FFL dealer.
They are legal to buy via PPT (Private Party Transfer), which is a FTF (Face To Face) transaction faciliated by a CA FFL dealer.
As a resident from another state moving into CA, you can legally bring with you any handgun not on the "approved" list (except "assault weapons") and sell them via PPT.
So, yes, you can make some money selling them, along with other handguns not on the "approved" list. But, it would require that you move to CA and establish residency there.
Kel-Tecs being sold in CA, were either purchased before the "approved" list was created, brought into the state by new residents or bought by LEOs & then sold to the public. Since, supply is low and demand it high, they typically go for 2-4 times what they are worth. Last time, I saw one for sale, it was a NIB 1st gen P-32 which sold within 3 days for $700. I bought mine (used 1st gen P-32, 3 mags, 2 holsters) from a LEO for $300 (friend price).