The reason most companies would not want you to

link to your own private web site would be they are not sure of what claims you might make. You could say, “This product cures cancer.” and then link it to your corporate site. A reputable MLM company in business for many years, was closed a few years back because of claims of the distributors on their own web sites and on radio.
This hopefully prevents that from happening. The question of ebay, is that people put it on ebay and undercut distributor’s prices. It is unfair to the person who is working the business retail or sometimes it is even cheaper than you pay wholesale.