Consider splashing black and/or red. Use
Dark Ritual,
Culling the Weak,
Vessel of Volatility, &
Seething Song to make absurd amounts of mana very quickly. With a few other tweaks, I could see fairly reliably playing an Ulamog or Emrakul by turn 5 this way. The possibility of
Defense of the Heart on turn two is awesome. It would be easy with
Dark Ritual.
I believe that
Time of Need would be your most optimal way to put Ulamog or Emrakul in your hand.
I could be wrong, but I'm pretty sure it's the best option around 1 USD.
Best of luck!