The trouble with buying them legally is you can't mod them. Well, I guess you could buy it and then just to find a ROM and hack that and be morally in the clear.
Mother is basically unplayable in 2015. The encounter rate is beyond ridiculous. I'm a little surprised they released it unmodified. Shortly before the official Nintendo release this year, someone put out a great hack that makes the game actually enjoyable. If you're going to play Mother, play this version.
If we're posting romhacks, this super metroid hack is absolutely amazing. An entirely new tileset, an all-new much larger map, new mechanics, AI, it could be super metroid 2. Highly recommended if you enjoyed the original. Oh, and the ending. The ending!
