Grass-fed/ finished beef is worth the cost because it is more humane. The quality of life a cow has roaming around open pastures is much better (and more natural) than a cow that is confined to a feed lot. The cow is healthier because it is not exposed to terrible sicknesses in tight feedlot living quarters. Therefore, the grass-fed/ finished cow does not need the antibiotics that a feedlot cow wold require to survive. You can't do much better than allowing a cow to live in it's natural environment, eating it's natural foods.