GameCube:Trusted Sellers and Hardware List

Stores
Black Dog Technology u/Citrus3000PSI - Modding parts

Castlemania Games - Modding tools, parts, accessories

Console5 - Parts and accessories

Digikey - Electronic Components

LaserBear Industries - 3D Printed Parts, Modding parts

RetroFixes - Repair Parts, Accessories

RetroGameRepairShop - Repair parts, Modding parts, accessories

RetroGamerStuff - Modding parts, repair parts

ZedLabs (UK) - Repair Parts, accessories, modding parts

Swiss Homebrew Memory card (Preloaded)
CastleManiaGames(US)

SD2SP2 (SD Card Reader):
Allows the use of SD cards greater than 2GB capacity 
 * Console5 (US)
 * 8BitMods (US)
 * CastleManiaGames (US)
 * Zedlabz (UK) (Multiple Colors)

Memory Card SD Adapter:
Only allows SD Cards up to 2GB
 * Zedlabz (UK)

XenoGC (MODCHIP):

 * RetroGameRepairShop (US)
 * HandHeldLegends (US)
 * Zedlabz (UK)

GCLoader PNP (ODE):
'' The belows are the only authorized sellers of real GCLoaders, almost all eBay sellers are chinese clones do NOT function correctly. ''
 * BlackDogTech/Citrus3000psi (US) -
 * GC-Loader.com (EU/NL Based)

GCLoader PNP Mounts:

 * Translucent 3D Printed by u/Digitehk (US)
 * RetroGameRepairShop (US)

GCDual:
''GCDual is an internal hardware mod designed to run GC-Video by Ingo Korb for the DOL-001 Nintendo Gamecube. It outputs analog video and digital simultaneously.''
 * CastleManiaGames (US)

Video Adapters
Unless otherwise stated, all of the below adapters require the Digital Media port on the DOL-001 models, or a modified DOL-101

Carby (HDMI)

 * Insurrection Industries (Carby maker) (US)
 * StoneAgeGamer (US)
 * CastleManiaGames (US)
 * GamesConnection (UK)

EON GCHD MKII (HDMI)

 * Amazon US
 * CastleManiaGames (US)
 * GamesConnection (UK)
 * StoneAgeGamer (US)

PrismHD (HDMI)

 * GamesConnection (UK)
 * CastleManiaGames (US)
 * Spelochsant (SE)
 * Verkkokauppa (FI)

Capacitor Kits

 * Console5 (US)

Controller Thumbsticks/Buttons

 * Zedlabz (UK)