I have seen these at williams sonoma.
I have also seen the "La Bella San Marzano" brand of tomatoes. So though they may sell some san marzanos under that brand, not all of the tomatoes sold under that brand are san marzano...
For example here are
La Bella San Marzano Cherry Tomatoes
And
these do not look like San Marzano either!
San Marzano's should say DOP on the can...
Please!