I have been flying and training for many years and I feel that it is just like any other industry. You just have to pay attention and be a bit street wise, nothing specific to aviation I feel. The main cost that is usually not included and can add up, specially when training abroad, is cost of travel, housing and licence conversions etc.
It would be the same to complain about the Motorway police because welcom break is overcharging....
I do agree with Gin Slinger that some of the CAA costs are a bit over the top.. (understatement..) On the other hand I feel that the guys doing do the work in the licencing office at LGW do their best to help you. They are always on the receing end of our complaints while in 99% of the cases they are only executing orders. :o