After swinging back and forth like a garden gate in the face of online criticism, Amazon finally decided it would let customers who don’t want ads on their widgets opt out if they pay an extra $15 for the new Kindle Fires it brought out last week. Amazon is using ads to keep the price of the tablets between $199 and $499 less than iPads. Ad-free Kindle e-readers cost $20 more. The company claims from its e-reader experience that “very few people choose to opt out.” Oh, by the way, it appears the high-end Kindle, due to ship November 20, doesn’t have FCC approval yet probably because of the skinny newfangled 4G modem Amazon designed for it.