I was just quoted $7200 including delivery for a 448 mounted on my 3320. I already have the power beyond kit installed on my machine. Your price seems high to me.
One franchisee has all the nearby dealerships except one? That would explain the pricing. Depending upon your location and how far you had to travel, it might be worth a 50 mile drive to save $600-$800. When presented with a copy of the cheaper dealers quote, the local guy might come down in price.