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The service uses Sonic's RoxioNow platform for content delivery, which makes it quite similar to Best Buy's CinemaNow (which is based on the same platform). The pricing, too, is very similar, as Alphaline Entertainment offers movie rentals for $3.99 and purchases at $19.99 for new releases.
Sonic and Sears plan a multi-phase rollout, which should eventually make the service available from a variety of connected devices.