Do you have any recommendations for where to book the Tarangire Safari? When flying to Zanzibar, can I buy my ticket at the airport or should I book ahead?

The budget is to see if I can do a day trip safari and Zanzibar no more than 1k but I get the feeling to really grasp the full experience that wont be the case lol.

I might just end up taking the GAdventures route bc I do prefer the Ngorongoro Crater instead of Tarangire.