I just recently moved into a house. It's the first time I've had a garage. I started looking at parking aids, and most of them were goofy looking and over priced. After scouring Amazon for one for an embarassing amount of time, I finally settled on the MAXSA Innovations Park Right Parking Mat. At around $15 it's cheap enough where you can't really go wrong by trying it.
It comes with double sided tape adhered to the bottom so it's easy to keep it from sliding around your garage floor. It's stayed perfectly put on my poured concrete garage floor in the three weeks that I've had it, and the car is easily parked perfectly every time.