For training treats you will want very small treats. Liver works well for that. You may use beef or pork. Pork, of course, is cheaper. With the cost of everything rising at an alarming rate, I have found I can make them cheaper. Also, I do not have to worry about the ingredients because I control them.
Cover cookie sheet with foil for easy cleaning
Lay slices of meat (liver, pork, chicken, beef....) on cookie sheet
Bake in 350 degree oven for 1.5 hours or until dry and done.
You can experiment with the time. For larger treats you may want them to be a bit more dry so you would increase the baking time. For training treats you will want them to remain fairly moist so I keep it at the time listed. Slice to desired size and place in zip lock bag in refrigerator. Will keep for week or freeze and defrost a bag at a time.
Hint: You do not have to buy large quantities of any one thing if you have only one dog. Often there will be small packages of meats after weekends or holidays on markdowns.
P.S. This is not vet advice. I am simply sharing my experience with you as I try to reduce the need to use processed treats and other products. As always, use your discretion.