Most likely Mexico.
There's a ton of cabinet shops just over the border and he's only a 2-3 hour drive.
JBL/Harman has a ton of their woodwork done there. KRK too.
China is too expensive once you factor in all the freight, duties, etc.
I've seen a bunch of these listings from other sellers on Reverb and eBay all at similar prices with speakers included. I'm guessing everything comes from the same factory and they can buy cabs and speakers wholesale pretty cheap. The pinewood is likely midgrade at best so that saves on costs. It also says in the listing it's butt joints & staples and doesn't appear to have internal bracing. That equates to less labor and materials to produce one. Also equates to a lower quality build.