Just like Ashiok there isn't much room for the new Elspeth planeswalker in other formats except Standard. It should do great in Mono-White Devotion lists that focus on a lot of smaller creatures that can attack as early as possible.
These types of decks are especially popular in online versions of Magic: The Gathering, since these types of decks are usually moderately priced. But that doesn't mean that Elspeth will stay in the "cheap" category. She may as well be the most expensive card in the deck.
If Elspeth, Sun's Nemesis goes up in price, then not too much, and should stop somewhere around $12 range.