A studio light kit is a great tool to have but not an essential tool for every reseller. It really depends on what you are selling. If you sell mostly small items that fit inside of a light box then you may not have much of a need for one of these kits. However if you sell larger items or if you sell something like clothing then this is a great buy for you. I use this exact light kit for all of my clothing pictures and they make a huge difference. This difference is especially noticeable with dark colored clothing. Before I had a studio light kit my camera would have a hard time focusing on dark colored clothing. The extra amount of light was enough to allow my camera to focus in correctly on my clothing items.
This specific kit I use by Cowboy Studios comes with 4 adjustable tripods, 4 super bright CFL bulbs and 2 lighting umbrellas. The tripods are in 2 different sizes and are adjustable. Also, the angle of the light is adjustable at the neck of the tripod. Because this is not something that I use every day I love that it comes with a carrying case. Everything folds up in this case and can easily be stored when not in use. I am always paranoid that the bulbs may break so I do put them each in their own padded envelope when I put this away just to avoid breakage.
Certainly not an essential for every reseller but in my opinion it is an essential for anyone who sells a good amount of clothing items. I have been very happy with this kit.