How much money you need to move to America?

I'm from the UK, London and my dream is to live in New York City. Yeah, a lot of kids say that but i'm 17 and putting in the work to get there grades wise so i can get the capital necessary. So yeah. Erm, my mum said it's like 250K worth of GBP to get there? But then my friend said 500k USD soo... which one is right.