X2 on the local butcher.
I found one close by that uses the tubed casings. Instead of me buying a bag of them and having some sit in the fridge as I don't make tons of sausage at at time, I will pick up a tube or two from him. The tubes he carries will handle about 7 pounds per hog casing. He cranks out a ton of sausage at his shop, so buying them in single quantities like this, I know he has fresh. I would rather do this than let them sit in my fridge for months. He charges me $3 a tube which is pretty reasonable IMO. He also has tubed sheep casings for breakfast links, but I have not tried them.
Use google and make a few phone calls to butcher shops. I bet you will find one that will sell you smaller quantities of very good grade casings. If you don't have a butcher nearby, try the grocery store. A lot of them also stuff sausage in house in the meat department. My local Kroger does, but they looked at me like I was purple when I asked about buying casings. But if all else fails, it's worth an ask.