Hi there! I just thought I would jump in since our situations are similar...our dogs weigh about the same, and I am doing raw "grocery store" style like you are! You do have a great selection. I wanted my dog (just one)'s food budget to be around $45 per month, so when I did some basic math I also came up with the goal of getting meat for under $1 per pound. It is not always possible, but that is what I try to go by when I am shopping. With chicken and turkey is is easy, for example that big bag of chicken you found...great! With beef, it hasn't been possible for me yet. But as I find out how the monthly costs are averaging out, I will add some beef in there.
I also go to a Meat Packers Outlet in my town and bought $33 worth of chicken, turkey and some organ, and it lasted for over a month. I just searched "butchers" in the name of my hometown and got a list, started making calls and found this gem. They cut it up to whatever size I want and they are so nice.
As for ziplocs, yes, reuse, don't put them in the dishwasher (the heat can break them down), and if you are going to reuse or defrost in them, the freezer kind vs. the storage kind are thicker and better. It's worth it to take some time to put everything in those, with two dogs you can keep at least one storage bag in your fridge and get through it without it going bad (probably two storage bags full).
It sounds like you are off to a great start, how are they doing? My doggie got SO SOFT once she was on raw for about 10 days.