That said, American wine—and California wine in particular—has a bit of an IPA problem inasmuch as there is a lot of overpriced, overproduced swill being priced exceptionally high by international standards.
You haven't addressed what I asked though. Are you sitting the boxes upright? Do they have corks or are these cheapo screw cap bottles?
Quick poking around Google... Italy, France, and Germany all have mid-tier bottles of their own domestic wine for far less than we (in the US) get any wine, domestic or import.
Often times, wealthy people buy wineries as a hobby to dabble in, but end up selling and calling it a day before it drains their cash. If you want to buy wine for cheap that is made in California, buy mass-market wine.
Smaller brands are generally expensive because that price is necessary to sustain operations, but most of the time that fails, and the owners end up selling.