D2K would fall under the "pirate-hack" category, which nintendo has and still does sue over, even for the NES.
There were plenty of them made for the NES and some still are. Games like adventure island have super mario sprites hacked in and then the game is sold as super mario 11 or something.
This fellow is using Nintendo owned characters, music, and code and selling it without Nintendos permission. For a hefty price, I might add. Also, if you read carefully, he is also selling the orignial donkey kong as well (selectable via start-up menu) without Nintendo's permission, which also puts this in the bootleg category and makes it more illegal.
Now had this fellow simply released this as a mame rom or was just charging for the cost of the parts, I wouldn't give a rip. I actualy think what hes done to the game is pretty cool. However, this fellow is trying to make money off of someone elses work both in bootleg and hack form, which makes it illegal enough that I will be forwarding his web address to NOA to see what they have to say about it.
-Harry