Source for klobasa?
Good question. Polish recommendations I can provide you easily. Czech and Slovika are unique and, unfortunately, I do not have recommendations for you.
But, have tried Bobacks and Polana? Both are polish. Bobacks is a sausage emporium, they have a huge sausage selection. located near Midway Airport.
Also, one more recommendation is Gene's Sausage Shop (Lincoln Square). I don't know if they carry klobasa but they would seem to be the type of people who can order it for you or, perhaps, help you locate it.
4750 N Lincoln Ave
Chicago, IL 60625
Don't forget to try Kurowski's on Milwaukee in Logan Square, few English speaking patrons here...it's right out of Warsaw, It's dirt cheap and quite cool. I find their products to be superior to Bobaks or Gene's. Also try Lincoln Meat market in Lincoln Square and Paulina Meat market. For fantastic Italian sausages, try Riveria Foods on Harlem in Elmwood Park (been around for 60 year s or so, will take you back to another era...dirt cheap too) and Minelli's Italian Deli at 7900 N. Milwaukee in Niles. Chicago is full of fantastic ethnic deli's. I would search the southside of Chicago and southwest burbs for Slovak/Czech specialty stores and restaurants.