Nelsoni are very good milksnakes to keep. As adults they generally have calmer personalities compared to some other triangulum subspecies. Be aware however that baby milksnakes, nelsoni included, are very spastic when held, unlike baby gophersnakes.
Milksnakes are more shy compared to gophersnakes IMO. Milks are less apt to eat in front of you (some will, but some will wait until you are out of the room.) This is part of their nature. But, nelsoni also happen to be quite the tolerant milksnakes.
Nelsoni come from warm, humid environs in western Mexico. However, they remain underground much of the time where it is cooler and drier. In captivity they do well in a cage that is dry. At shed time however you should provide a humidity box or a 15 minute soak in very shallow room temp water. You don't want the snake to have to swim to stay on the surface. Even 1/4" of water is often enough.
Temps are normal colubrid temps, like warm end of 82-84 deg and a cool end of whatever room temp is for the most part.
$100 for an albino nelsoni (are we talking albinos here?) is very good considering about 6 years ago they were like $1500 dollars each!