I have an iPhone going through Red Pocket, $29.99/month gets 250 minutes (which I almost never use) and 500 text messages. I have no need for data since I only am online at home or places with WiFi. Red Pocket goes off AT&T towers, so signal is good and wide coverage but at a fraction of what I was paying with Sprint.
As for Verizon... I have some words for them that may be inappropriate here... Had too many issues with them before...