Products vs. Attributes - set up dilemma

[fiddler]

I'm setting up a shopping cart for my client and thought Zen Cart would be the ticket, but I'm confused about how to actually proceed to get the results he's needing.

My client sells ad space. He sells the ad space based on first the nature of the Business needing the ad /adspace, then by State, then County, and the ad space price is based on the County (with the price determined by population of the County).

Since the ad space is virtual, there is no shipping.

I've set up the Category of "Business" (as there might be other categories in the future, I think), then have Product Categories under that, such as "Automotive", "Agriculture", "Health & Medical", etc. Under the Category of "Automotive," I have the products: "Body Repair," "Towing," and "Transmision Repair."

The CUSTOMER will first select a type of Business (like Automotive), then a subcategory (like Body Repair). Then the CUSTOMER will select a State, then a County and the price will be determined by the County selected, as some Counties cost more than others because of the population within that County. There is a base price of $150/mo. for any County, and a sliding scale based on a percentage to be added to the base price for those counties that require higher fees.

So my question, I guess, is, (1.) should States be a product under each repective business (meaning I should move the product of "Body Repair" up to a subcategory of Automotive), and (2.) or should States be an attribute, and if so, how do I add the counties as a subattribute?

I was thinking, since every "product" has to select a State, then a County, that both State and County would be considered attributes.

My client wants the States and the Counties to be selected by dropdown boxes.

For what it is worth, I do have a list of all the States, with all their Counties, with each price in an Excel spreadsheet I can modify and upload via phpMyAdmin, or if anyone has a better suggestion, I'm all ears.

If Zen Cart is not going to work for this project, please let me know. If it will work, how do I proceed?

Thank you for your time concerning this dilemma.

The url for site, by the way, is virtro.com/cart

[fiddler]

I forgot to add that each "product" (such as Automotive/Body Repair) can only be sold once per County. Then it will be officially "sold out" until that contract is up - for however long that takes.