What is the rifle going to be used for? If you are looking for a long range/high magnification scope, you have to watch as the eye relief diminishes as the magnification increases. A good quality scope will still provide you with a decent safe eye relief when set on high power. It is never a good investment to cheap out on a scope, but neither is there anything wrong with finding the best value for your dollar. You must decide where that balance lies.
On the other hand, if the scope is to be used as a big game scope within the terminal limitations of the .308 Winchester, high magnification is not required, and a low powered scope set further away from the eye allows you to shoot with both eyes open, creating the benefit of seeing the cross hair suspended in the air, rather than with the sense of looking through a tube with it's restricted field of view. The quality if the scope is measured by neither eye relief nor magnification, but rather by it's ability to seal out moisture, repeatable adjustments, the quality of it's lens coatings, and it's optical clarity. Beyond that, you must simply choose the scope which best suits your requirements.