Cotton Linen Substrates can be found on sites such as Alibaba. On larger quantities, they will even offer to customize watermarks and add various basic features.
The issue is; as we found out- is that 1) the industry is purposefully very difficult to navigate and find a good price to quality ratio.
Additionally 2) sourcing from China can be quite risky. There are various examples of Cold Storage Holograms being leaked into the market.
How can you protect your product from a company that could notice the profitability... and simply start selling your product themselves?
We are open to discussing with you further.
EDIT:
Some examples of what I mean...