I'd recommend buying a cart; you can find a trash game for cheap easily at a Goodwill, Gamestop, etc. (or your equivalent thrift shop, game shop, etc.).Yeah thats what ive found. I only want eur for smash but ill just wait until i buy a cart or wait for cart less safehax.
I got a cart only of Skylanders: Spyro's Adventure (impossible to play since no portal, don't care to) for a few dollars; something like that or a DS shovelware game should be enough.
(I got the Skylanders to extract a private header, but that's a separate issue)