It seems like you pay up front with cash and video making before and after new parts, then you get discounts from a few parts companies. The companies write off the discount as advertising, and the middleman keeps the first payment for their time and overhead.
I would prefer to have more of a choice for where I buy parts, but this could save you money in the long run if you buy a lot of parts from the companies listed and they keep giving you a discounted price.
"We have created a Star Wars civilization, with Stone Age emotions, medieval institutions, and godlike technology. We thrash about. We are terribly confused by the mere fact of our existence, and a danger to ourselves and to the rest of life.”
― from Edward O. Wilson, The Social Conquest of Earth.