https://www.chewy.com/yummy-chummies-original-salmon/dp/112155?utm_source=bing&utm_medium=cpc&utm_content=Yummy%20Chummies&utm_campaign=f&utm_source=bing&utm_medium=cpc&utm_campaign=Shopping-Product%20Targets&utm_term=1100000000553&utm_content=Yummy%20Chummies
You can make these really cheaply with canned salmon or tuna, flour, egg, garlic powder, pinch of salt.
Spread it out on a cookie sheet, score it and bake it