I realise overheads may differ from location to location, but how can there be such major variations as $3750, $3999, $4500 for the same item quoted by different dealers?
From the more expensive dealers I'd expect better after-sales service, from the cheapest I'd expect no after-sales service. That time of having someone happy to spend potentially hours fixing your problems is where I would see the difference from $3750 to $4500 going.