Please do Terry. I havent been to that area and appreciate all the info I can get on parks I have yet to visit.
The 400b must be exception or possibly because it is a popular place.
For instance my last trip to Phu Toei I paid 240b total for 6 nights camping which was 30b each night to camp 30b for the car and 30b entry.
The notice board said farang price was 100b but they only charged me 30b.
Off to Mae Wong Monday for the week, will do a report when I get back.