I’m not aware of any single listing. But just about every resort on the lake that runs an ice house business will have leads on shacks for sale. Just about every resort will have a “For Sale” bullitin board. If you take a drive around the lake you will find a lot for sale. Especially now.
The resort I stay at has a website with a listing. I’m sure other do also:
Fishemens Wharf – Items for Sale Page.
The Mille Lacs Messenger newspaper is also a good place to check out.
Mill Lacs Messenger Classified
You should also try contacting Hunter Point Resort. George run a pretty big opperation and may be able to point you in the right direction.
Hunters Point
Good Luck.
-J.