Oblivion Sower is one of a number of good, cheap Magic the Gathering cards from the Battle for Zendikar set.
But in Legacy, he's been seen as a four-of in a tournament winning Eldrazi deck. He also sees a good amount of play in Commander. EDHREC has Oblivion Sower listed in over 2800 decks. Still, with a Duel Deck foil printing, there are a lot of copies out there in the wild.
Legacy demand alone won't drive this card in the way that the format used to, but it's so widely usable in Commander that copies will always be selling. But, if a Modern deck happens to win a major event with multiple copies in the 75, it's likely this card could end up spiking in price.
If a price spike doesn't happen ever again for Oblivion Sower, it's hard to see this card ever being worth less than $1. So if you need your copies, now is as good a time as any to pick up Oblivion Sower.