Do I need a breast pump if I’m wanting to breast feed?

Ftm here and I want to breast feed my baby so bad, but the thing is I don’t want to go spending all this money on a breast pump if I don’t need too, I’m thinking about going and buying the Haakaa and pumping one side while feeding her and putting want comes out in the freezer/ refrigerator for later use or if I have her with family etc. would this be okay? Im just trying to not spend 150 on a electric breast pump if I can do the same with a haakaa