Just depends on how fancy you want to go and where you live. I get blocks of Tillamook cheese here in Idaho as well as some Idaho "craft cheese. I can get the blooks at the local grocery store. Walmart and Costco usually have it as well. If you are looking for specialty cheese Costco has some in store and more can be ordered. If you need to have it mailed to you, you can try this place: https://delidirect.com/wisconsin-specialty-cheeses/. I have not used them simply because I can get most anything I want locally, and they seem to be a little pricy to me.
High temp cheese
At what point do you put the high temp cheddar cheese in the sausage mix, before grinding or after grinding?
Robert Tartaglia You will want to put the Hi-Temp cheese in after grinding and at the very end of mixing. So if you grind everything first and then add your seasonings and cures (if needed) then get everything all mixed into the meat, the correct level of protein extraction and then add your Cheese for the last minute or so, just to get it evenly distributed throughout the meat. If you added seasoning between grinds then I would still do the same you just would have to mix a little bit less.
The grinding would smear the cheese and the point of using hi-temp is for it to retain at least some of its original form.
Let me know if you need anything else!