Mine is a Sport Dog. I went for low-mid range in price, definitely not the cheapest I could find, but couldnt afford the top of the line units. I think it was around $200. It has the beeper function, which I think it good to have, and variable buzz, which I think is standard. It also will do short buzz or stay buzzing with another button. I think it will run two collars off one sender. Its rechargable of course, any decent one should be. I had the batteries get flaky with it still in warranty. After doing diagnostics with the rep on the phone they just sent me a whole new unit, a bit better than the one I had.
I'd avoid the super cheap ones like the plague. I know someone that bought one. Uses store bought batteries, and generally doesnt work very well.
Some of the best advice the bird dog trainer gave me, dont ever let the dog know its you doing it. Never threaten them with it, or wave it at them. If they chase deer, let them think the deer did it, and call them back like your best friend,..."Oh poor fluffy!, did those naughty deer do something mean to you?"
One of the things many people never quite get, never call them to you, then punish them. Always try make coming to you a good thing, or that they arent going to get their butt beat. Even when I'm mad, I'll scold the dog but not in a way that she thinks its scary to come to me.
Mad at dog, no buzzing. Dog does something bad, and in the process, Bzzt! No fluffy! Usually just the buzz does it.
Mine was chewing on my seats and seatbelts. Scolding her wasnt effective, and I wasnt able to catch her in the act. I'd sit in restaraunts where I could see her. One time, I saw her grab the seat belt to chew on it, Bzzt!, she never did it again and I never said anything about it again.
I've had mine over 3 years. I've actually buzzed the dog less than 15-20 times total. She stopped bolting, (1 buzz) stopped chasing deer, (1 buzz) stopped getting close to snakes, (1 buzz) generally comes when I call her, (several at different times when she didnt react when called), stopped chewing on the seats and seatbelts (1 buzz).
She gets really excited to go in the truck, and gets up and down on her bed every few seconds, wants the window open to bark and hang out, and generally sort of spazing about getting to go. Telling her to get on her bed works for about 5 seconds. Beeping her she gets in the bed for a while, and if she gets off, I dont say anything, just beep, and she gets back up and lays down. I've never used the beeper as a warning before buzzing either, just to get her attention.