Slacker Plus Radio $30 ($2.50 a month)

Slacker Radio has a deal right now for $30 a year with a yearly subscription (breaks down to $2.50 a month) to Slacker Plus radio.
Go to:
1. https://www.slacker.com/upgrade
2. Click the "Special Offer" Banner over the 3.99 plus offer.
3. Sign up for a yearly payment of $30
This is the cheapest legal adfree streaming service I have found. They always have the best artist discovery and curated playlists.