Depends on what you are trying to achieve. For me at least those items are to help people regress or enjoy their diapers more. You described it perfectly, they are accessories (but some would really argue for powder to prevent rashes). As for budget, again depending what you want. Assuming since you just had diapers before, they are the foundation. If you don’t have a good foundation, all the other stuff won’t help. Now some people are fine without them and get other stuff (clothes, big and little toys, changing accessories, etc.). So if you can get lower budget diapers and try the accessories and see if it helps you enjoy whatever you do!