Virgin Mobile is offering the iPhone 5 for $549.99 + a $70 account bonus for new users. This phone is eligible for their no contract $30/month (yes, $30) plan with unlimited data.
This is a great deal if you're wanting to bring down your monthly phone bill. If you were on a plan from ATT or Verizon, this could save you around $1,000 over two years. Highly recommended.