buy an old nes
and uh, you should be able to DL roms, dump them to a physical rom, socket this rom on an NES cart.. and just reprogram when you want a different game.
guess it would technically be illegal, but it's not like you can even buy NES carts anymore.
That or go to a garage sale and find a box of 50 carts. nintendo makes the same amount of money either way.