If you're going to be the first to hit Physics (a very expensive tech at its era) then yes you are paying a rip off price compared to everyone else behind you. But.... techs like these either give you a Great Person for being the first, or unlock some nice wonder.
In this case, you get a Scientist. So really, its' the second guy who gets there that seems to be getting the real shaft. His discount doesn't make up for your prize, and if it does, then his discount worse than the discount behind him, so he's in the worst spot no matter how you look at it.