The answer to this question is 'yes' and 'no.
Usually when people look to purchase a pre-trained dog, it is because of a specialty hobby or need that the person has:
- Sled dogs
- Dogs for duck hunting
- Dogs for fox hunting
- Therapy dogs
- Seeing-eye dogs
- Personal protection dogs
- & More...
There are some other avenues that you could explore if you're more interested in just purchsing a pre obedience trained dog for your home and family. You can look into rescue dog or prison training programs where the dogs will earn CGC certificates before they are placed. Once in your home, these dogs will require a period of adjustment, but it will be a good start.
Pre-trained specialty dogs, like the ones mentioned above, will require a huge investment of both time and money if you intend to see them live up to their potential.
As mentioned, pre-trained dogs aren't cheap. Additionally, it could be daunting to try and find one pre-trained in the specific areas of obedience that are important to you and your family. These types of pre-trained obedience dogs start at $5000 and can easily cost you over $40,000 for specially trained and certified Personal Protection Dogs.
The unless you have a very specific purpose in mind for your new pet, it's probably best that you pick a dog you feel an attachment with, let him accommodate to his new environment (your home) and then either enroll him in obedience classes, hire a professional dog trainer to come out to your home and work with him, -or- simply get a top notch and comprehensive Dog Training Course like the one below...
No matter which route you decide to take, we're sure that you are about to find your new best friend, who will love you forever, and never break your heart :)