Your assumption that there is such a thing as a more or less desired logos is completely invalid. It is a completely subjective issue. Even if it wasn't subjective, they are certainly geared towards different industries.
The social influence mechanisms are the same as a SAAS Product adding features (which again are of subjective value, and not necessarily an improvement in service, just in perceived value.)
At first I thought the pricing model was backwards, but then I considered that for each logo that was purchased there is an increase of social validation which makes it more tempting for other to buy. I also immediately thought that he marked 17 as sold to give the impression that anyone bought his logos
There are two cars in a lot sold for the same price. Any buyers cannot resell them and must buy them solely for their own use.
One is a Bugatti Veyron fresh off the factory floor, and the other is a 2nd hand 10yr old Ford pickup.
A 55yr old farmer shows up. He lives out in farm country at the end of a 4 mile driveway that looks like this: http://imgur.com/a/SsusC and he needs a vehicle for general farm work.
Sorry, in my part of the world a pickup truck more often than not is just called a car, with the word "truck" usually reserved for larger cargo-carrying vehicles.
Road signs in California for weigh stations will say something like: this lane, trucks only (no puckups). Car is used to mean either in most conversations, so I knew what you meant. I liked your analogy and found humor in the fact that the answer to your question was in a way hidden in your question. I intended to answer your question and share the humor I found but I was short on time and instead my comment looks snarky.
The social influence mechanisms are the same as a SAAS Product adding features (which again are of subjective value, and not necessarily an improvement in service, just in perceived value.)