Question: I want separate "Buy Now" pages for each of my sales associates. How do I do that with the standard edition of the Web Manager?
The version of the Web Manager that you have does not assume multi-tenancy, so it shows all plans on one page. However, you don't have to use that generated page on your website(s). If you like, you can create your own web page, or a page for each of your sales team members, which contains links to their individual plans.
If you want different plans for different groups you have to define them, even if they are identical. Otherwise end users would all sign up under one group.
Note that each plan on the "Plans" page (Setup : Plans) contains a column called "Link." Hover your cursor over that link graphic and you'll see the link for signing up for that plan. You can copy the link for each plan and use it as a tag on a separate "Buy Now" page for each team member. You will have to manually create and maintain each of those separate pages.
You might want to consider the Multitenancy PlugIn. It contains features designed to support Partners and Resellers.