Expanding ecart product pricing options

I have an installed e cart with about 10 products. All works as it should be.
Client now wants to have the same 10 products, but at different price points for different groups.
Example: the public page product would cost $30 but a re-seller could access a page where the product would cost $15.

I can used password protected folders for the different presentations, but what can I do in the cart to present the difference in pricing? I thought of adding a field for sorting, so that the discount presentation page would only show those with a sorted entry. But perhaps this is already in the cart somehow that I haven't considered. I see options groups, etc, but am not clear about how it works. I also considered a coupon system, but when I tried to make sense of a tutorial on that about a year ago, I got totally lost.

If you can point me in the right direction, I'd be grateful. Thanks as always.