You can get along without mineral - some people can more than others depending on their soils.  The question is can you gain something from it?
Mineral costs $20-30 per cow per year if they get it 365 days (stuff like fly control and aureo will add to that cost, but they are not mineral costs).
So, you would need  3-4 more calves out of 100 cows, or 15-20# more weaning weight on all of the calves (or some combination of the two) to pay for it.
In our part of the world, it pays for itself.