So the retailer has their own page, or the "unique url" lists all products by that retailer?
Playa is for linking entries, 1 entry to many. using it to link 1 to 1 is a bit overkill.
Based on the information provided, I say you want to use Categories. So that when creating a product, you assign it a category (and the categories are the retailers).
If the retailers have their own pages and not just used to group products, then you could just associate an entry in the retailers channel to the relevant category.
So "Joe Blogs Outlet" manufactures "Widgets".
Widgets is assigned the category "Joe Blogs Outlet"
Going to /products/joe-blogs-outlet lists all the products from that retailer (this can be done a variety of ways, one of the easiest is to capture it in template group "products" and use the index template, then use Low Seg2Cat to identify the category in one of URL segments
The retailer category could have additional basic fields assigned to it to display details about the retailer in this instance.
But if you wanted the retailer to have their own "proper" page and EE entry instead of storing information in the Category fields, you could have another channel called "retailers", create an entry called "Joe Blogs Outlet" and assign it the same retailer category as the product, then you'll be able to link the product to the retailer and both will have their own entry.
Alternatively use EE relationships.