I would recommend you to start your business with a reseller account. It is the most logical way to start a web hosting business. It requires only some $12-$20/Month. You can choose your reseller account from the many available reseller hosting providers out there.
Why not start with a VPS or even a dedicated server? Well, there is no point in doing that, unless you already have a substantial amount of clients to begin with, plus you already know what you’re doing. If you are starting from scratch, there is no need to spend on a VPS or a dedicated server.