If you tell me what kind of specs/quantity you need, I can send to one of my best friends, who happens to be in the paper business. He’s based in Mexico, but he has some American customers and keeps a lot of inventory in Laredo. Very nice and honest guy too. If he can’t do it, he’s likely to know a source.
Uline has a facility near Dallas. www.uline.com Their styro shippers are very high quality (though not the cheapest). We used them when I was ITB in Dallas.