I love our wood stove and most of my wood has been free, but it has not been very economical. The missus just really likes it a lot because our den is 80 degrees in the winter (70 in most of the rest of the house, and 65 in the back bedrooms). We installed new last year for about $2800 and it will be many long years before we recoup that cost, I think we are saving perhaps $200 a year over the cost of our heat pump, as electricity is cheap in VA and our winters relatively mild. There is a lot of work involved as well, splitting the wood, stacking, moving the wood, gathering kindling, clearing ash out, constantly loading the stove, etc.
In Wisconsin though I could see you recouping that cost a lot quicker if you can get the wood free, your burning season is a lot longer and colder than where we are.