I have the HP iPaq 1710 with Tomtom software and car kit it retails for £299.99 in the shops and can be had for £235.99 via some web sites.
Down side itâ₠¬ÃƒÂ¢Ã¢â‚¬Å¾Ã‚¢s not Bluetooth so you canââ‚Âà ‚¬ÃƒÂ¢Ã¢â‚¬Å¾Ã‚¢t go walkabout and does not have a plug for an external antenna, but I have had no problems in my car or van and it puts me right outside my customers house which is quite cool.