RE: How much can I get a used permanent ice shack for?
You could make one for close to nothing. I come from a long line of ice shack builders and they are nothing to put together. Scratch up any materials you can and make a shack. One thing that will save lots of money is ripping 2 by 4s in half. The half 2 by 4s are plenty strong.
Keep it simple and throw a plexy glasswindow in for some light.
Dont wast your money on one that someone else put together.