@Blossum mentioned in a post that we can now opt out of the Special Offers on the K4 (but apparently not the K3) by changing a setting on the Amazon Manage Your Kindle / Manage Your Devices web page. I captured the option window and attached it below. A lot of people kept asking for this option with the K3 SO models, so it is nice that Amazon listened and gave K4 SO model owners the option to unsubscribe to Special Offers. You need only click the option and pay the $30 difference and your SO becomes a non-SO model.

To unsubscribe to Special Offers, go to your Amazon Manage Your Kindle / Manage Your Devices web page. In the Subscribe column, click Edit next to your K4 SO. Follow the instructions on the screen that displays.