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Why would you only use it once? It's a pretty good insurance policy. Also, you need to do collar intro or you could ruin your dog. Buy something nice. You won't regret it.
Only time a bird dog should be run without an ecollar on is at home or at a field trial. Deer, porcupines, skunks, snakes, bear, cougar, coyotes, roads...lots of hazards out there that a dog needs to be "persuaded" is a bad idea to mess with. Just make sure the dog understands how to "turn off the the juice" or you'll spend the rest of the day looking for the dog. Proper collar conditioning is key.
What about the Garmin??