Best Buy is having a Free Smart Phone sales event right now.
Of course, to get a free phone, you have to sign up for a contract, but many of the phones being offered go for $150 and up even when they are coupled with a contract.
You've got your choice of Android and Blackberry phones as well as some smart phones that have their own o/s if you're not into either. And you can choose from Verizon, Sprint, AT&T, & T-Mobile.
The best deal seems to be the Droid Incredible with a Verizon plan. This phone is 'normally' priced at $599.99 and typically discounted to the $150 range.