Hello,
This can be done with some customization to an open source shopping cart. If you want subdomains to use the data base of the wholesale products then it has all kinds of issues....such as who wants to own a "store" at a subdomain or where you dont control the real check out process.
A better solution would be to have a shopping cart platform and the wholesale store. The owners use the platform and host it. You can customize the shopping cart so the "parent" store (the wholesale store) actually updates the substores run by the resellers.
If the resellers are selling all of the same products and they just need to add content to a site and have a new template, then contact
www.sourcefuse.com. We
www.inventorysource.com have worked with them before to help other clients trying to manage a small wholesale program like this and I am sure they can custom design a solution for your needs.
Also, you can work with a hosting partner and platform system to give you your own turnkey sites which you can sell to your clients. This might be more then what you need, but if it is then contact
support@inventorysource.com and we can see what might work best for developing a solution.