Manage product catalogs on sub-sites from main site

I'm starting to think this is a weird request as I've not found anyone yet who does or wants to do something similar but here goes:

What I'm looking to do is have a multisite on which I allow clients to register sites. The principal selling point I have at this point is a number of pre-populated product catalogs that my customers would like to offer on their site. Each customer will want a different combination of catalogs and I would like to allow them to pay at any time and add whichever catalog they desire to their site.

Some important parts of this process are that I want the product data to remain in sync with the main catalog with the possible exception of the price which customers may need to adjust to their liking. Also, I would like the product images to not be duplicated endlessly and would prefer that all customers referenced the main product images rather than adding them to the media library of every single site.

I have seen many users do things like what the New Blog Templates plugin allows which would be to populate a site with content at registration but my desire is to be able to turn on and off these catalogs at any time for any of my customers.

At this point I'm really just looking for 1. ideas on how this might be accomplished 2. examples of anything even remotely similar being done in WordPress and 3. possibly developers willing to take on a project for me if it turns out to be possible.

Thanks for any ideas.