Taking a group class is not as time consuming as it seems and can provide high quality training for a very reasonable fee. You do have to spend about 20 to 30 minutes a day doing some work at home but you should be spending that time with your dog anyway.
If you feel that a group class is not something that you have time for you have a couple of different options.
You can usually find a trainer that will provide you with a similar sort of conventional obedience class in a private format that will take a bit less time and be more focused on you and your dog. Look for a trainer that has dogs of their own to supply some socialization for your dog. Of course there still is that training at home that you must do.
Another option is to move to a totally different method of training such as a remote collar. Dogs typically learn a great deal faster with this method because it creates total attention when you are working with the dog. Dogs become far more reliable with remote collars. Trainers that use remote collars will work with you to develop your skills and can have all the basic skills firmly entrenched in your dog in two weeks. With this method, you do all the training yourself under the guidance of the trainer. So although the two weeks is fairly intense in terms of training it is a safe, reliable form of training that is well set in a very short period of time.
The final option is a board and train. With this method you drop your dog off at a kennel and the trainer does all the work for you and you go back in two weeks and pick up a trained dog. You will be paying for a professional to work with your dog daily (usually several times a day) and you will also be paying for the boarding. Also included in the price is the guarantee for further training should it ever become necessary. This will make this the more expensive choice. This method results in a very well trained dog that only requires maintenance to keep up the level of obedience. If you chose a kennel that does boarding to train your dog, your dog will usually receive a free brush up when they are boarded.
Remote collar training has the added bonus of being able to correct a vast number of problem behaviours.
It is vitally important to seek out professional help with remote collars so that the dog learns first how its actions can turn the collar off. Simply putting a collar on and pressing the button will create a confused and frightened dog and will make future training much more costly and difficult.