You can buy them here.
https://store.alpine-usa.com/Acuradvdsales/naviorder.php
It's pricy, $185 and shipping.
They do updates in later of the year, in November or so, so if you buy it now, a new version won't come out until 11/09.
I bought my update two years ago, and realized the new construction / changes in freeway nearby did not get updated until the year after... I was bummed out as that was the only reason why I bought the new DVD. Almost $200 later, still not 100% updated...
Sometimes you can find newer ones on eBay. Those are probably stolen out of new cars. They can still be pricey, though, as many people bid on them. Just make sure you buy the right color DVD for your car, and they should work.
