I have a 2008 Dodge grand caravan. I have the factory 4 speaker system with the standard radio. I am looking to get a aftermarket Pioneer stereo with GPS installed. I was told I need a $150 wire harness to install the stereo. This makes the total installation price to $300 dollars. I am wondering if this is correct. I can not imagine how a wire harness to go from a factory 2008 stereo to a after market system can cost this much. anyone replace the factory stereo who can give me some insight?