Dredge players have been really happy to see this card in Theros Beyond Death, especially for its two red mana Escape cost. This means that it can be already played from graveyard on turn two with the help of Stitcher's Supplier and Stinkweed Imp.
If this works as intended in Modern, it could easily drive the prices up to $20 a card. The Vengevine archetype could also support this, if it turns out to be as good as it looks.
In any case the official tournaments are starting soon and that's when the situation regarding the price of Ox of Agonas will be solved.