I know what you mean Hanna. Whenever a poster links to a site there is usually a link on that site that reads "business opportunity" or "member status" or something similar that tips off the fact that someone is getting a commission off your purchase (likely the person who directed you there). Multi level marketing or straight commission, I've seen lots of these posts pop up lately.
One thing that amazes me is how much these products cost!! I think it says something about how desperate people are to heal themselves, that these "health product" sites can make enough profit to survive means they are convincing a lot of people to purchase their stuff.