1). I used a bike tire inflator. Way cheaper... Is it that different from the Leerburg thing?
Hmmm should look something like this??
Planet Bike Air Ship CO2 Tire Inflator
2) for us it was a very temporary tool. We used it for dog aggressive behavior but I think my dog is pretty sensitive to correction. It worked in the sense that he thinks twice before reacting negatively to a dog. However at a certain point he became too anxious about it and would just shut down. It also didn't help that a huge truck used their air brake and it made that pfffffft sound x100.... That was the turning point. Anyway, it did work in the sense of not going after dogs but our v ultimate goal is comfort around other dogs and it didn't help there .
"Comfort around other dogs???" I've not heard that term?? So I'll ask you to define your conditions.
My dogs are "comfortable around other dogs" to me that means my dog will stand calmly while dogs bark in there faces, from behind fences. And will, stand behind me calmly while daddy deals with charging strays!
They can go the Vet's office and not make a scene. Well one occasion when my Am Band Dawg, acted nutty with a lab but no harm was done, no conflict, he was just being an idiot!( And my wife was at the leash on that one ...would not happened on my watch.)
And they don't act like fools when they see dogs on walks. To "me" that defines "comfortable around other dogs." But I did that by having a "Zero" Association" with other dogs policy. No "Dog Parks," No "I Thought My Dog Was Friendly People???" And on walks if other dogs approach?? I give ground if need be to gain space. It was years before they ever played with dogs and the those dogs were also balanced. Three strays brought them into the house released my dogs from "Place" after a few minutes and everybody had a great time.
But I have a "Hard Core" no other dog policy. No Dog, I do not know comes close enough to mine to do them harm. "I don't know you. I don't know your dog, you keep your distance I'll keep mine!" Works out fine.
If a "Zero" other dog policy works for you I got it covered. But the dogs on the beach thing all playing together happily?? I don't know, as it's not my thing. Most likely the same things are done?? But since that was not my goal. I'm not the guy to coach on how to produce that result??