There are literally hundreds of types, styles, shapes, sizes. There are also a wide variety of types of materials such as, aluminum (diamond plate or smooth), white steel, black steel, powder coated, painted, polished, and more.
The best way to determine what your customer wants is to ask a lot of questions. What do they plan on using the box for? How often will they be in and out of it? Hey, we all see that box for $200. What you usually get for that is a box that is a much thinner gauge of material, usually built from scrap and riveted together and has very inexpensive hardware. I call this a "get by" box. For a customer that uses the box on a constant in and out basis, this is just not for them and will only create an upset customer in six months.
I always try to explain to the customer that a box that cost $650 weighs three times as much, has a much better, more secure locking system and will outlast that $200 box ten-fold. It will last through several trucks!
What's more important is keeping those valuable tools secured. Many contractors carry $5-8,000 worth of tools in these boxes! Would you wrap a gold bar in brown paper? No, you would want it in a safe!
Think value, security and strength. Get the best product for the job and you'll have happy, loyal customers.