Why not just make one? It's fun to build and if you don't like it, you can sell it for more than what it cost to make.
There are thousands of ice fishermen here on the Saguenay river and I have yet to see a store bought shelter.
Almost everyone has a shelter of some sort. It's a must because from mid december until the end of march, the temperatures are often at -20 and it's always windy. Many just have 3 panels on a homemade sled. They open the panels and sit the sled on it's end to get out of the wind. You can add some plastic tarp to make a roof and front if you want. A lot of people use a metal tobacco can, a roll of toilet paper and some alcohol to make a hand warmer.