Mice and ultrasonic and electronic control

I have mixed feelings on these plug in electronic ultrasonic devices that are supposed to control and repel mice. I know that Victor has a decent line of them and apparently people buy them or they wouldn't be on the market. I guess in ultra sensitive accounts where baiting and trapping are not allowed then the last resort would be for mouse proofing the area and using devices like the Victor Mini Pest Chaser or some other kind of electronic mouse control device. I still believe the best kind of devices like this is one that you can change the frequency on so the rodent will not build up a tolerance to the sound that is supposed to be chasing them away. I guess these electronic mouse control devices have their place and if they are not too expensive then they are worth a shot.