The C64mini comes with a joystick, but what if you want a second one? Where do you source them from?
Apparently, SNES style joysticks (the one from INNEXT for example) may do the job. Retro pie compatible joysticks are worth checking out too: see raspberry pi, 8bitdo and core electronics. The PS4 dualshock may work, but is about 10x the price.