eHobbyAsia have some upgrade parts from Hephaestus in stock:
Hephaestus New Upgrade Parts for GHK AKs / M4 is available eHobby Asia
Hephaestus CNC RPK74-type Steel Flash Hider (14mm CCW)
Hephaestus AK Tritium Front Sight Post for AEG/GBB (CNC Steel)
Hephaestus CNC Steel Trigger for GHK AK Series GBB (Type A &B)
Hephaestus AK Charging Handle Extension for AEG/GBB
Hephaestus CNC Steel Flat Trigger for GHK M4 GBB
Please check the link for Hephaestus new item at eHobby Asia Store