The one that works for me are the sonars which I bought from Walmart over a year ago. These are two ultrasonic boxes that look like sound speakers. You plug them to a power outlet and it keeps emitting a sound that is very loud for mice, but which the human ear cannot hear. I know it works because no mice ever comes to my door, and I keep it on all the time. One time a mouse came through I think because someone was chasing it in my floor, and by mistake it went through my door. As soon as he got one foot close to the boxes the mouse fell on its back with legs up on the air, kicking and in some kind of pain. I had to pick it up and put it out of its misery. This indicates that these boxes really work.
I don't remember the brand, but for sure you can get them at Walmart. I think it's about ten or fifteen bucks each.