Free: Contests & Raffles.
Decoys are ok as long as they are not motorized. Yotes have really good hearing and can hear that motor even if you cant.
I've seen some set up in stores. Some are really noisy. I never used them since I'm not big on set up time for predator hunting. Where i used to hunt you needed to move a lot to find them and if you wanted to setup a decoy every time it would have been a lot of extra time and walking which means more human scent around and fewer areas covered. If you were in a spot known to produce and were going to spend time there anyways finding a quiet decoy would probably be beneficial.