Corrected: Amazon challenges Apple and Spotify with new music streaming service

(Deletes reference to the Echo recognizing Michael Jackson as the King of Pop after Amazon retracts example) By Julia Love (Reuters) - Amazon.com Inc on Wednesday launched a full-fledged music streaming service with subscriptions as low as $3.99 per month for owners of its Amazon Echo speaker, accelerating the industry trend toward more flexible pricing after years of sticking to $9.99 subscriptions. The new streaming service, called "Amazon Music Unlimited," lets users access a vast catalog of