Although I don’t know all that much about dogs, I would recommend you ask a few standard questions in relation to how he/she (the trainer) goes about training the dogs, the techniques they use, etc. Also, maybe finding a couple of different options to get some different ‘quotes’ on price, so to speak. From what you’ve said, it sounds as though this trainer is not part of an organization. Maybe you should also consider a dog-training school of some sort, that might have lower prices and particular breed specialists.