Free: Contests & Raffles.
I use 30-06 mineral supplement made by The Whitetail Institute. It's a granular form of mineral that you mix in with dirt. I use it for my trail camera set ups. It's great for finding out what kind of bucks are in the area, but I don't know how good it would be for hunting. In my experience the deer primarily are attracted to it in the spring and summer.
Salt blocks are legal
..... please be mindful of where you guys put these salt blocks. If you have ever seen in the woods where there was salt once, you will know what I mean. It looks like a bulldozer went to work and it can be very destructive.