Hacking Flashcart for both NDSL and Old 3DS?

[Question Master]

I had a fake R4 a couple years ago and it would not allow me to play some of the "newer" games that came out on NDSL like Harvest Moon: Tale of Two Towns, so I am looking for a cheap flashcart that works on both the NDSL and the old 3DS.
I would like one to play DS games and only DS games.