While the front side is good enough to see play on its own, the fact that it only has four defense counters makes it relatively easy to flip (a single Sheoldred, the Apocalypse attack gets the job done), and the backside offers a very powerful creature that can defeat a battle or kill a planeswalker each turn while potentially generating card advantage as well
Howling Mine (T1, Ext, S) If any one card in Magic is the poster-child for card drawing, it is Howling Mine
Enchanted is rarer than epics, but more common than iconics
This means youll be able to cascade into other high mana value cards
[But] there's no shortage of people buying expensive Magic cards even in this economic climate
If you're looking for another X spell, I might suggest Voracious Hydra - As it is cheapish $ wise, acts as removal and a creature or just a really big beater