I earn 1000 ip a day. Spring Break. So which of these 4800 champs should I get.

Depends on which lane you want.

I'm thinking of getting her at the moment but shes mostly just top. Fizz can jungle and go mid, even top sometimes.

My current champs I might buy is either or or

If you want more bang for your buck Id chose either naut or fizz as they can be played in more lanes so you'll get to play them more often.

Nautilus is in the top 10 most objectively fun champions. His movements feel interesting, every ability is responsive and has good feedback, he always has impact on the game, and he's very forgiving.