What are you going to be using it for? Just for vehicles or is there a possibility you will use it hiking, backpacking and such? If you are just looking for a protable to transfer from vehicle to vehicle I have the TomTom one and it is around $200 look @ bestbuy I think they have them on sale now. It has the text to speach and they automaticaly update so you don't have to buy the CD's to update them, saves $$ in the long run. It also has a battery that is supposed to last like 3 hrs good enough for short trips.

If you are looking for something that might be used hiking/backpacking the Garmin E-Trex series would be good to look at. I have the base E-trex that has no roads just for outdoor stuff and they are around $100, you can get the models with the maps for under $200, I have never used the E-Trex that has maps. The only thing with them is that they are small screens mostly made for portability.

Good luck on your decision, I know that there are a ton of them out there and just giving my .02 on what I know.