My Prius model year 2006 came in with the maps stored in a DVD that was updated in Feb 2005. Car is still going strong, giving me 45 mpg in summer and about 40 mpg in winter. No problems, no issues. Except for that stupid map-DVD. Toyota thinks the updated DVD is worth 200$. And furthermore, only an authorized dealer technician can do this impossibly difficult task of ejecting old dvd and inserting the new one, labor at 80$ an hour. And the local dealer charges 20$ a day "storage fee" if you don't pick the car up when they call you to say it is done. It is a rip off. No one in right mind is paying for this stuff.
A few years ago I updated the map DVD in my sister's 2006 Prius. The DVD came with instructions and it was easy to do. The dealership sold me the DVD and did not try to insist that only an authorized technician could do the job.