Dean makes a good point about the portability of aftermarket products. They're great in rental and loaner vehicles, but I'll have to disagree with the part about paying $800-$1000 once. That's like buying a laptop and expecting to keep it indefinitely. Yes, my Dell laptop from 1995 still runs, but its utility is limited. I'm on my second aftermarket GPS receiver since 2000. Sooner or later, the old technology becomes inadequate. My first GPS unit had manual routing and limited memory for maps and POI interest, so I upgraded. If interest is a concern, include the cost of nav in your down payment. I say get an OEM nav and a portable one for those times when you need it.