If you were to find 3-5 more products on ebay with similar markup then you could aggressively market an ebook that exposes those products. As a preview, you could just give away one of those products on the sales page to prove you are the real deal and can actually provide sellers with more by simply buying your product.
I think "value based" pricing would be the best here i.e. a high-end product, and also implied by a high price, would be that there may have only been a small number of purchases made by other competitors when in reality it might just be the opposite, sort of counterintuitive.
As you said, it really seems to be a great system to work.
also the profit margin is very high, but it's also depends on the competition of the product to sell easily.