hog & sheep intestines or casings are pretty essential for making sausage
Other than that: cure #1 as you already mentioned.
Other than that: meat, spices, herbs etc and than the hardware:
Grinder and different size grinder plates, stuffer or stuffer attachment, meat hooks, string, thermometers for checking the temperature inside your smoker and an instant read thermometer for the internal meat temperature, knives, cutting boards, throw away gloves might come in handy if you don't want to mix the meat mixture with bare hands.
Ah, and ice packs to cool down your grinder. I am still looking for a flexible ice pack that I could wrap around the grinder to keep it cool.
And smoking wood, shavings or dust
And plenty other stuff that's just cool to have