Do's & Don't (How to Adopt)

So I already have a beautiful baby boy at home but my next LO(baby) we want to adopt (I was adopted & it's something I always wanted to do but I don't know the process or good websites)..my question is what is the cheapest or best way to adopt? Children are pricey in general I just don't believe I should spend so much money to an agency when the money should go to buying food, crib, etc for the baby (also any little tips I should know) *I always thought it would be nice to adopt directly from a birth-parent so I can meet them etc.. but I don't know how to do that..honestly open to all ideas..all I know is I can't handle fostering I don't want the possibility a losing a LO I just bonded with