Find a local poultry cutting/boning plant most give away chicken carcases as they have to pay to get rid of them anyway, I’ve been feeding this type of food to my dogs for years, you can add some veg, or rice, if you mince it, can do so much more with.
The Dod Food Company supply a huge range of minces and bone, also very reasonable prices. I would do the slaughter house thing, but i run my own business and just don't have the time to go round and collect/mince stuff myself. Pre done packages out the freezer before bed is as easy as!