I never used them, but Aquafaux have many types and size, they are the most realistic... I don't know if they ship world wide, nothing on them on amazon and they are pretty expensive. But they have contact info published.
Is there any reason for wanting artificial plants ? Like a crazy cichlids tank or something ?
Because, buying a led lamp, fertilizer and filling a tank with real plants is cheaper in the long run... You can even add a cleaning crue and have all the benefits of real plants for your environment.
Personally I'm not super good with plants... But I still prefer replacing a real plant that I'm not able to make thrive than treating silk plants for stubborn algae.