You have to contact Renesas for pricing and availability, I believe. The product was supposed to start sampling in July 2013 but the product selector on the Renesas website shows it as still in development.
I believe one of the primary reasons for moving display buffers to external DRAM has almost always been cost. More performant solutions might use fast onboard RAM (similar to cache on a modern CPU core).
So this might be an interesting presentation - since the proposition is increasing perf and lowering cost (relative to a modern DRAM based solution). And of course DDR perf is increasing (e.g. - DDR4) - so it's also a moving target.