Navi in a non-navi 2006?

I'd like to know as well, even though I'm quite happy with my TomTom...

 

Nav system is already a VERY pricey option. I can only dream what it would cost to install after the fact. I would go look at Garmin.com and pickout one of their nice ones (the $700 one that reads street names maybe?). I currently use a Garmin i5 (think tom tom) and is very happy with it. It's user interface is much slicker then the Prius one.

That all said I'm waiting for a 07 Prius #7 or #8

 

There's been a similar thread for putting a OEM NAV system into an '05. It finally came down to getting a third-party system would be better as there's lots of things to add (in the '05 it would be a new steering wheel, new rim around the MFD and wiring). Even if you went to a junk yard and could get the parts, you would probably pay more that a really decent third-party system. Whether you want a portable or built-in would be up to you.