Chris nails it on NG. They are highly sought after beers, in the past having distributed out of state, but for the last number of years only available within Wisconsin.
Belgian Red is one of my all-time favourites, a "desert island" beer for me. It's one of the first beers that I found to be truly revelatory, and remains to this day.
Their brewery is a sight to be seen, an incredible facility which is a standard of many modern US breweries, insofar as the design allows visitors to do a self guided tour without getting too close to any of the equipment.
Concur that a trip to Madison is time and money well spent. It's a great little city with many fun bars, a great beer scene and good people.