Probably the simplest way to do this would be to just create 7 different versions of each product and then set up a page for each product that only permits access by one group of users. Unless someone did some hacking they would only be able to add the product(s) visible to them to their shopping cart.

To completely prevent someone from ordering a product from the wrong level you would have to add some logic to the checkout steps to validate the product(s) against the users' groups.

That could work but the thing is they have around 40,000 items they want imported... I wonder if 280,000 items would have a performance issue? If the number of items isn't an issue... this would be a simple solution. Any thoughts on the number of items?

The number of products wouldn't be an issue. What you can do, is use events and add products in different prices places etc.

When you say use events... where is this functionality? I'm not positive what you are talking about. Is this the "discounts" area of ecom?

Events are not really beginner friendly, you need to know how to code, if you go to the docs section and search events you can find it