[onewhippedpuppy]

I've been looking for the same thing, my trusty Garmin needs a $50 maps update (couldn't find my wife's sister's new house in Tucson) and I'd prefer to buy an iPhone app with on board maps and ditch the additional device. So far I've only found the TomTom and Garmin that offer turn by turn and on board maps. Both are about $40, the Garmin seems to get better, though still mixed, reviews. One big pro for the Garmin in my book is the ability to use it on multiple devices at no extra cost, my wife has an iPhone as well and Tom Tom seems to require a subscription per device.