Do any of the main sail makers use Hydranet as standard? and what is the premium?
It is expensive... Maybe a little overpriced. Incidence and Elvstrom are the two biggest users and I think get the best deals on it. NZ sailmakers pay more due to the shipping, going though the local dealer etc.
Most of the seconds grade hydra-net finds its way to NZ and Aus which makes it more affordable, but more likely your sail is going to lose its shape due to issues in the weaving/finishing.