Buy the best you can afford, and don't sweat it. Do not obsess about each and every cut of meat. Some will be better than others. It all averages out.
If you've cut industrial seed oils out of your diet, you've taken care of the majority of the O6 overload. The second best thing you can do is avoid restaurant and takeout food ALWAYS, since you have no control over the oils they use.
Cooking pricy grassfed and pastured meats at home will still be 1/4 the price of the equivalent restaurant meal.
Save up and buy 1/2 or 1/4 of a grassfed cow.