In the United States, there are several companies that supply paper to large, commercial printers. I can go in there and buy from them, although at a much higher price than the large printers pay. However, some of their paper is only available if you buy by the "pallet." Kelly Paper kellypaper.com is one of those. I do not know how the printing business works in Oman.
Another place that I have purchased from is called: www.geographics.com/. I do not know if they have operations in or near Oman.