Look guys, the software & maps are going to cost you around $100 regardless of the brand. Some are a bit more but there aren't any street nagivation software worth looking at that sells for much less. When you step back and think about it, that's actually one hell of a deal.
In my car I have the Mapsco paper street level atlas for my home county of McLennan County Texas (Waco area) and it is about 150 pages and cost $24.95. That's just for one county alone and it still doesn't have any find or routing features. I have to pour through the index to find some street I don't know then find the right page and search the right grid. It would cost me thousands of dollars and I'd have to pull a u-haul trailer just to carry all the county street-level maps of Texas with me on paper. With software like Mapopolis you get up-to-date maps for every single county, street, and town in the entire US and Canada for just about the cost of four paper atlases.
Anyway, if you like to mess around with maps and tinker with your settings. And you like to customize things like adjust all your map colors to whatever pleases you. Then get Mapopolis. It's the best by far if you like to tinker and mess with the program. On the other hand, if you only want simple navigation guidance with voice and the 3-D routing displays that don't really show you a map but just a big graphic arrow to follow like a video game then get one of the other packages that are more oriented towards routing rather than map display.
I got a Seidio powered cradle and wired GPS for my hardware direct from Seidio for $119 (I have an Axim X5 without bluetooth) and bought Mapopolis maps separately from Mapopolis for $99 for a total package cost of $218. I don't see any packages that are really cheaper than that. I also installed a permanent mount in the car because I didn't like either the suction cup or vent mount options. I got a pro-fit VSM Legend mount for $39 to install on my Toyota Sienna dash.
http://www.pro-fit-intl.com/VSM/
If I were going to do it again I would stick with Mapoplis for my software as I'm totally happy with the software and maps but I would avoid Seidio. You can read my Seidio customer service horror story on another thread.
For hardware I would just get one of the new CF cards antennas from buygpsnow.com or semsons.com and get the free Arkon mount that comes with it (I've found that a wired mouse antenna is unnecessary in my car because the angle of the windshield give the CF antennas plenty of sky. And I don't like the clutter on the dash). Then I would just get a DC power adaptor to run the Axim off the car cigarette lighter. They cost about $10. I think I'm in the minority but I never use the sound or voice navigation so I don't care about speakers. I can't stand having it chirp and chime all the time and talk to me so I just keep the sound off.
If you have bluetooth then the 338 seems to be the preferred unit on the various forums. I've seen nothing but good reviews.
If you are like me you'll probably find the mapping software and GPS antennas all pretty much work fine. By far, the most difficult part of setting up a satisfying car GPS navigation system is finding the right cradle for the PDA and figuring out how best to mount it in your car so that it is clean, easy to see yet out of the way. And so that you can easily pop out the PDA when you park on the street to avoid tempting a smash and grab thief.