Buying bulk probably rock salt will be cheapest. The other thing I would suggest is check out your prices on red trace mineral salt at the closest feed store. It has all the stuff animals need in bulk package. Farmers add it to feed for stock animals. Red trace mineral salt was only a few dollars a 50lb bag years ago, today ????
The last time I bought some red mineral salt it was around $6-$7 or so. Not expensive. Just buy you a white salt block, those work well for attractants too. Find a good place where the soil is loose and dig a hole and burry it. Make sure it's a place that will get exposed to the rain too.
As far as attractants, you can try peanut butter. I hear it stirs their curiousity some. Haven't tried it though. Cheap.