Try
www.nationaldiscountdoor.com
they have lots of good deals on steel clad pre hung doors. Lowes and Home Depot can also special order just about any type of sidelite set up you wish.
also, since you are in a very cold climate state I would reccommend a good storm door to keep the sun light and the extreme cold out. Youre RO (Rough Opening) is all you need to take with when ordering a new door.
Go with decent hardware/locksets that have finishes for holding up to cold weather, such as Hickory Hardware or Schlage.