Yep, regular old Italian Sweet sausage. Should be easily available at most any grocery store. They aren't frozen, so check near the meat department.
One problem that I have with these as compared to say a Jimmy Dean product or such, is that they can vary greatly in taste. Like I said it is a fresh product, and I am not aware of any brands for them. I have found that the best ones are generally form a butcher or an Italian Deli. Failing that I would test a few different supermarkets, and see which one tastes best.