I've put out the mineral blocks like you buy for cattle and have had pics of bobcats, coyotes, deer, and hogs licking it. Only $6-8 and usually last several months....I don't mind spending a few dollars to help out the deer even if the benefit is minor.
I've also had really good luck with Lucky Buck mineral. I spread a little out in several areas throughout the year and always get a bunch of pictures of deer at the sites.
We put salt and mineral blocks out year round, something is benefitting, has to be wildlife so in my opinion they have some benefit. Price is cheap enough.