Here is what i would as for. We have a Costco and a Sam''s here. From what i can see they handle pretty much the same grade of beef in whole pieces. They are USDA choice black angus for the most part. This is what i would look for. If you want to spend the extra money for Prime well that would be up to you. Second when you see the grade i mentioned look at the ends for marbeling and the least fat cap and tail [whole strip]. Dont expect uniform steaks from one end to the other. It just dont happen unless you get a center cut piece out of it. The larger end will have the most waste and are the worst cuts out of the whole piece. Again, check out the sales in your area, the grade of beef, and take a visual view of the steaks you are buying.
Also try buying chuck eye steaks for a change. Next best thing to a rib eye and at half the cost. That's the only steak I buy except at times if a good Porterhouse is on sale. Bottom sirloin steaks are also a good value but need some marinading. Bottom line is try not to get to technical with the numbers you mentioned above. Yes i have been a butcher for many years and i should know my meat of course and i'm trying to help. Try finding a good butcher where you live that you can trust and most will try to be as helpfull as possible. They want your buisness back and not a one time sale. It is also important that you prepare each steak properly for most need different tactics on the grill. There are enough people on this site to help with that issue as well. Reinhard