Personally, I wouldn't go for the $ to have the car come with Nav. However, I just did buy myself a toy, the Garmin Nuvi 350. I'm still in the process of fully installing it, but let me tell you where I'm at and how satisfied I am.
I got a car mounting clip from ProClip, around $35 including shipping. The clip ismate- black plastic and clips into the separation between the lower vinyl part of the dash and the aluminum upper part, just to the right of the a/c control. The bottom part of the clip hooks into the panel below the a/c assembly. This is easy to do and in no way mars the dash; and being black it fits into the decor rather nicely. The clip is angled towards you, it is small and quite unobstrusive. I took the black self-sticking Nuvi mounting disk and adhered it to the face of the clip. The Nuvi is mounted to its windshield bracket and the bracket suctions to the clip. It is easy enough to dismount the Nuvi-windshield bracket and transfer to another car's windshield. BTW, the Nuvi is silver and matches the aluminum dash very nicely. Furthermore, the ergometrics and functionality of this set up are perfect! The set up in no way interferes with the passenger's comfort and is very easily managed from the driving position. Of course, if you passenger acts as a co-pilot, the Nuvi can be easily turned towards them for thier use.
As I said I'm not finished with the install, as the Nuvi is now working on its battery. As soon as the heat/humidity here in SoFL abates, I'll be installing the hardwire aspect. Simply put, I've gotten a 12v adapter recepticle and will plug in the Nuvi's power cord into it. This is rather bulky and will sit in the glove box (would have liked to put the adapter/plu combination somewheres in the fuse box area, but there jsut isn't enough room). One wire from the 12v adapter will go into the fuse box and the other wire will go to a ground (all hidden from view). The Nuvi's power cord USB will snake out of the glove box, run under the dash and hook into the back of the Nuvi. Once again, all wires will be hidden except for a little bit of black wire that will eminate from under the dash into the Nuvi. I know some will say that I could easily use the Nuvi's power cord and just put the power plug into the cig lighter, but that's no fun and how ghetto can you get?