Retro 9 Pin Joystick to USB Converter : 4 Steps (with Pictures) - Instructables
USB Joystick Adapter from Retronic Design on Tindie
9 Pin Joystick to USB Adapter
USB Joystick Adapters – breadbox64.com
C64 Joystick Adapter | Hackaday
Dual 9 Way Atari/Commodore USB Joystick Adaptor
Connect USB Joystick to Commodore C64 - Hackster.io
USBJoy2.0E adapter - Extended Version. Connect your Atari Amiga C64 joystick to PC! Develop your own usb device! - Polish electronics for 3D printers, CNC, robotics, retro computers
Amazon.com: Retro Games The C64 USB Joystick for PC : Video Games