Meh...
I'll certainly pay the extra if I get in, because Balliol is fantastic for PPE with Cerberus etc, and personally I wouldn't have chosen another college even with the charge, but I think that it is totally unreasonable for them to charge the additional fee on students who have already applied without knowledge of it. Alot of people apply pretty much arbitrarily. But on top of that it's just the general principle that people should know what they are signing up for when they sign up for it, not after. And once you've chosen your college there isn't really any backing out.