There is absolutely nothing in the 800 range in the duluth area with the exception of fedex and some old nextel licenses. SLC is at last I heard, discussing ARMER versus Analog or Digital narrowband VHF (NFM). Other than that, people will be remaining on the old Legacy VHF systems.
Mn/DOT is the System Administrator of ARMER and every individual radio must have their permissions on the system, every talkgroup and every Site approved by the State Radio Board. Radio Techs that do the work on the system, of who there are less than 300 I'd bet, all have to pass background checks equal to that of a Federal Law Enforcement officer... If the systems finds a radio that has hacked its way onto the system, they can remotely "Brick" the radio making it a $3,000 to $5,000 Brick requiring a $500 system reactivation that can only be done at the Motorola Depot in Chicago... there is a way to get radios that access the system, but they are evaluated on a case by case basis and typically only allowed to members of the news media...
Long and Short of it, Per usual, I agree with Matt, buy a cheap VHF radio form one of the local radio shops up there, but dont expect it to be less than $300, otherwise peruse FleaBay and look for something... Most professional quality radios can be programmed with a Transmit Lockout... When I program my Moto HT1250, I lock out frequencies that i dont have permissions to use such as State Patrol or Federal frequencies. You also may have luck just purchasing a Motorola Minitor III (Fire Pagers)which are pretty affordable and can be set to be always monitoring and having the motorola dealer up there program it to Dul PD 1...