I do not condone piracy of any kind, so the main point of using an emulator for not paying games is completely unvalid, and speaking about this in many emulation forums will get you either big backlash, or even banning.

The point of using an emulator is to play games from older consoles without the need for the original hardware, or to play the games at higher resolutions, better framrates, or with cheats and mods, and finally, to preserve legacy.

All in all, just rip your games or your friends’ games to get your own ROMs. This is what I have done for Dolphin: every Wii/GameCube game has been backed up from my Wii games, or my friend’s games.