Looking for some advice regarding Ubercart and the sale of Permissions

I'm looking for some advice.

I'm working with a client who will be switching to Drupal with Ubercart as their primary e-commerce system. Part of our content delivery has to do with subscriptions. We have several hundred products, and we want to be able to sell a subscription for each individual product.

So, if you want to buy a subscription to X item, you pay your $$$ and Drupal assigns you the role. I know Ubercart can do this with its core functionality, and you can restrict access to the node with the content_access or taxonomy access modules. Ubercart explains this here: http://www.ubercart.org/docs/user/3366/selling_site_access_role_promotions

Here's where I get a little iffy. My understanding is that we'll need to have a taxonomy for each individual product and a role with access only to that taxonomy to make this work. If I buy product X, I CANNOT have access to products A, B, C, etc.

Does anyone know of a way to do this so there are general roles (1 day, 5 days, 1 month, etc.) that can dynamically be applied? So if I buy product X, the 1 day role can be assigned and only be applicable to that product, not EVERY product in the store?

Any information would be appreciated!