Justin clamp is a nice item to have in the equipment case, but it's more useful in tight location space than studio. I actually never use it that way in my studio.
Camera tripods are overkill and inflexible as a light stand. Itís good to pick up a couple of used medium-duty light stands as a starter.
Another good thing to have is a human being called assistant. They cost more and youíll have to order food during your work day but itís usually worth it.