Upgrade NAV System

I have a 03 Prius, and I have not had a new DVD since I bought it. I am tired of the NAV system routing me all through brown Phoenix since the DVD is so old.
I called Toyota and asked if I could get a new DVD, and they said "Sure for $250" - what really irks me is the system cost $1500, and now for $500 I can get an aftermarket one that does way more than the one that is installed.
Is there anywhere I can get an aftermarket DVD that had later maps for less than $250?

Thanks,
Eric