My best hint is that You get hands on a manoamano which You as well can visit through the internet. In the printversion at least are weekly many announcements of local companies featuring any kind of product, including everything related to publicity and print business.
Then, next step could be to ask in papelerias for their providers, they should at least know who can deliver it. In this case they would bring it to Your company.
And finally, if You need larger quantities I would recommend to visit Guadalajara, because everything in Vallarta costs about 50 % more.
In the afternoon I will ask some locals if they know something about that, if i can get information ill add a new answer, best regards.