The best deal out there for GPS in my ever-so-humble opinion is a refurbished Garmin iQue 3600. You can get it for about $250 on eBay and sometimes on deal site like Woot.com, and it comes with Maps for the whole USA. It comes with a cradle that sits on your dashboard (a bit tight on my 2006 Vibe, but workable) whose power plug goes into your cigarette lighter socket, and includes a nice and loud speaker. The screen is big enogh for my uses.
http://www.amazon.com/gp/produ...=UTF8Plus, it is a Palm unit, so you can bring it with you for other uses, and use the built-in address book to store your destinations and waypoints. And for anything else you may want. Plus there are a lot of add-on programs to add functionality out there, most for free. You can even get a program that overlays satellite maps on the screen, so you can see the pointer showing exactly where you are on the terrain.It is compatible with both Mac and PCs for syncing (though for initial setup and loading of maps, you DO need a PC or VirtualPC on your Mac).The only downside is the battery is weak, so you probably won't want to use it for hiking, unless you have an external battery pack. I can't recommend this GPS highly enough. We brought it to California and Minnesota (I like in CT) for weddings this year, and we were the only guests who never got lost driving between the various sites.