You can do it yourself if you have the "know how". Do some research, read books, watch videos, join a training club. Delivering to hand may take an experienced person if you don't do your research, but, the dog may pick it up on his own with repetition. I train 3-4 times a week, but I have have access to land right outside my door. Seems like these days I have a lot of fun and get more thrill out of training than actually hunting. I can train all year and enter Hunt tests during spring to early fall. Hunting is kind of the reward for just 2-3 months out of the year. My Lab waits at the door for me to get home so we can train, he absolutely loves the time out there and he stays in shape all year.
Not everyone has the time though, nor the land access. That is where the Pro's get their business, and most of them do a good job. If you were happy with what your trainer did before, you could take your dog back. It does take a lot of time (and in the case of using a trainer...MONEY) to get a polished dog though and it all depends on what your expectations are too.