The show is getting bigger and better every year, this costs money, the landing charges per seat (including ticket fee) is going to reflect that. I daresay it's also a way to quelle demand as I bet there are more aircraft wanting to fly in than there are slots available.
It's possible to get in for free this year (as it is every year) courtesey of The Times Online. Ask for free tickets and you shall receive.
Complaining about trade stands etc. is just bizarre; every show of this ilk does exactly the same. Go to Hickstead yesterday - how many horse-related business do you think have trade stands around the show ground?
Personally I think it's an excellent event. I love the diversity of the machinery on display and in action, I love wondering up the hill to the rally stage and the top paddock and there's simply no other event of its type in the UK that gives you the kind of access and experience that you can get at the FoS.