Great article, thanks for posting that.
My favorite source for heirloom apples in the greater Chicagoland area is Brightonwoods Orchard, in Burlington, Wisconsin. Basically, you get off I-94 at the Mars Cheese Castle and head west for 10 or 11 miles. There's also a cidery on the grounds called Aeppel Treow that makes hard cider.
We actually discovered the orchard by going to visit the cidery. Now we've become addicted to the apples and have been up virtually every weekend for the past 5 or 6 weeks to get more. I'm eating two apples a day, thinking maybe I can keep two doctors away!