Lily,
This may be a little late, however...
Petco had a Christmas sale a couple of years ago, just a couple months after we got Boots.
I picked up a handheld ultrasound trainer for $10, and the birdhouse ultrasound for like $35.
The handheld also had attachments at each end which allowed you to put it on a leash, and worked great for leash training, and really help with the pulling. Was just irritating enough that he figured out real quick how to stop it himself.
The birdhouse was initially used indoors when he discovered he could bark, and really got to enjoy it. Especially in the late evening.
It worked so well, indoors and on our patio, that he apparently learned not to bark when I am sleeping. If my wife is gone to work, and I've decided to sleep until 11:00, he'll come up and nose me awake or gradually climb high and higher up on me until I awake and take him out.
At the local dog park which we visit almost daily, he's one of the quietest dogs there, unless he's wrastlin with one of his harem.
I'd say try and get one from a place with a decent return policy. Don't think it can hurt.
EDIT- Oh yeah, he loves the handheld so much now that he comes running to lick it when I use it (rarely). Somehow, its a very positively reinforced thing for him.
My Sheltie doesn't bark out on walks or when just going outside to go potty. She can also go hours inside without barking. However, she barks like crazy when she sees the vacuum, lawn mower, hears a knife on the chopping board, the sound of the recycling bin being moved to the sidewalk, unrolling tape, etc. Has anyone had success with an ultrasonic bark unit or collar?
