Found the card again..Land of the Giants Hosta Farm had a very nice exhibit this year.
Milton is not far from Janesville ..and a nice drive from the Madison area. http://www.landofthegianthostafarm.com
Just be warned--Land of the Giants is not open as a retail nursery on a day-to-day basis. You need to phone and set up a time to come visit. And if you know what plants you want Jeff will dig them up for you in advance.
They also have an open house on Memorial Day weekend. They'll have a bunch of plants potted up for sale, plus Jeff will dig whatever you may want a piece of right from the ground. Again, be warned...if you plan to have a plant dug you're probably going to be waiting for a while during the open house. When I was there last year I was told it would likely be an hour or so wait. (And it was hotter than blazes that weekend with no place to sit and wait.)
Jeff's plants are REALLY nice. I have a few of them and they've done well. I'm looking forward to getting more this year!