I used to go to fleet farm and buy 2 50lb bags of trace mineral, 1 50lb bag of di-cal and 1 50lb bag of salt. It was under $80 total. I made the mistake of adding 50lbs of molasses one year and the bears loved it. Didn't do that a second time. The di-cal is supposed to be the part of the mix that helps to grow bigger antlers but the deer don't really care for the taste of it by itself so that's where the rest of the mix comes in. That would last me 2 to 3 years depending on how "fresh" I would keep the mineral sites. I was only running 2 sites on my 115 acres and good activity at both. Now I'm lazy and my back is shot so I just order Redmond trophy rocks and bags of the mineral ready to dump. Usually just put it out once a year in the spring and call it good.