Safest Travel System

We are looking for a safe travel system for our baby that we can ideally use until babe is at least 3 or 4. I’m looking for as many “double duty” things as I can! Looking at the cost of everything is just terrifying, sticking to a budget seems impossible. I’m planning on wearing baby but I know we will need a stroller at some point or another, I just don’t want to use it for a few months then get something else when baby outgrows it. Any tips mommies out there?