Definitely make your own broth,rather than buying! It is SO MUCH MORE economical. I use a rotisserie chicken (actually buy a whole chicken from my local, free range farmer and put it in my counter-top rotisserie). Then I use the carcass (not skin) & veggie scraps to make the broth.
ALL of my veggie scraps go in a bag in the freezer for the next pot of broth. And cook those bones until they are soft. You'll get the benefit of the collagen. (Google bone broth for more health benefits)
I have 2 qts in the freezer right now. When they're gone, it'll be time for another chicken!
I don't worry too much about a tad of extra fat. I just downgrade on my olive oil a bit & figure it all comes out in the "wash". As long as I'm losing and I'm still in ketosis