Is there a cheaper way to get a map update DVD?

my name is Sal and I'm the new owner of a 2011 Prius 4 with the Solar Roof/Nav Package with 58k miles.
There's a lot I like about it so far, its just that the Navigation Maps are very outdated. Can the Maps be updated with a dvd, flash drive, or both?
Can you buy legitimate updates on Ebay, or do you have to shell out big bucks to get it at the Toyota Dealership?
BTW, I've attached a few photos of my car below.