I have an XL series Tom Tom, I LOVE IT. bigger screen, lots of options, works like a champ! I personally use the standard windshield mount most of the time depending on which car I am in. however there are quite a few mounts that will work on Ebay, just depends on which GPS you are using.
and not to mention, in my Tom Tom, I can put ANY CAR I WANT in as the car image. If you decide on a Tom Tom, go to this link for the DIY I made on putting a picture of YOUR car in your Tom Tom.
http://www.camaro5.com/forums/showthread.php?t=91620