If you have a time machine, you could get a 3DS XL for really cheap on release day with the Future-Shop "trade 5 games" deal. I managed to get my XL for 50$ and 2 old games I didn't play anymore. Considering I then sold my original 3DS for 120$, that was an incredible deal.
If you only live in the present... there's no deal that I know of right now. You might have to wait for the black friday week to get something decent. :/