Those Neoflash things support many different cartridges with adapters and they do it well.

This is quite cool, problem is, most every cartridge in existence is already dumped, so why would one need this nowadays? And as a joystick adapter, it's quite expensive.

I think this is more on the side of "look, I'm legally playing ROM cause I have the cartridge".

Anyway, since I'm here, where can I buy some kind of universal controller adapter? I would love to play more N64 games but is awful with a PSX controller...

This is quite cool, problem is, most every cartridge in existence is already dumped, so why would one need this nowadays? And as a joystick adapter, it's quite expensive.