Many places sell them, on line and in stores (Cabela’s, Sportsman’s Warehouse, etc.). Something to consider, is how much you make at one time? 5 lbs., 10 lbs., or more? I had a 5 lb. stuffer, but usually made 10-20 lbs. of product. It was a pain in the posterior to keep having to load the hopper. My 5 lb. stuffer never held 5 lbs either - more like barely 4. After 4 years, I finally gave in and bought an electric stuffer, a 20 pounder for L*M. They have occasional sales, and I got mine for a greatly reduced price on a 24 hr sale. They are pricey otherwise, but worth it if you are making large batches, especially by yourself. The manual/hand crank stuffers aren’t the easiest to use by yourself, but it can be done. I think a lot of use have done it and still do. But a helper is definitely nice!
The stuffer I started out with came with plastic stuffing tubes. If stainless steel tubes are an option, I’d get those instead, or buy the size you need as an accessory. The casings seem to work better on those than the plastic, in my opinion. Good luck, and I’m sure you’ll be happy with your stuffer! Makes a better product!