I have had experience with dr lam and did not have a positive experience. Some of his methods made me question his credibility.
I think it is very unreasonable to ask for so much money by anybodies standards unless you can garantee results. His articles on adrenal fatigue are however very good and a good guide. You should be doing things like removal of stressor, diet change in the first place anyway.
I suggest you make an agreement with him that unless he can bring about an improvement within an agreed timescale e.g. 3 months, then he will refund half of the costs or something. Make sure this is documented.
Also note that most of the guidance he gives is already in his article and you can do it yourself e.g. remove stressors, remove bad diet(caffeine, sweets), get nutritional diet etc. The only thing he will add is the dosages of certain supplements.