Sausage casings and pork fat in Madison, WI?
I'm in Sun Prairie and make my own sausage, as well.
I KNOW that Fraboni's, on Regent, carries some casings. I'd give them a ring to see that the sizes are those that you need.
Pork fat is something else. I have had a terrible time with that. Here's a suggestion, though: Reach out to Jordandal farms - http://www.jordandalfarm.com/index.php
Using the "Contact Us", you'll probably get Carrie.
I purchased two pork bellies and some clear white pork fat from them a few months back. The pickup point was right over in your neighborhood.
I got enough fat for a BUNCH of batches of sausage.
Koolwhip has great advise. Sam's is a fantastic place for product.
Another good place is Woodman's. They cryopack pork ends/scraps into approximately 5-pound packages.
Personally, I love it. My triple-batch for andouille calls for 15 pounds and 3 packs suits me to a tee.
If you'd like to back-channel with a fellow Dane County sausage maker, please let me know.
While I certainly wouldn't call myself an expert, I have been successfully making sausage for years. Assuming that you're grinding your own pork, a regular pork shoulder (i.e boston butt) should have a fine fat to pork ratio. I usually just go to Sam's club and buy the pork there. I'm not from the Madison area, but I've always found that any place that makes their own sausage would be willing to sell casings/extra fat. Good luck!