Have the prices for 2600 E.T. carts climbed over the years, or is these buyers paying a premium to own a "Genuine landfill ATARI E.T. game, complete with certificate of authenticity" etc.?
General ET carts are cheap AFAIK. The landfill ones are special.
Thing is, the article mentions only a few hundred carts. Rumor had it that many thousands of carts were dumped, and realistically, such an operation would never have been worth the while to dispose of only a few hundred, or maybe a couple thousand carts.
There were rumors of tons of them, but what they found was warehouse excess and I don't think it was that much of it.
There are a few documentaries made on it. One was a full movie from the Angry Video Game Nerd (people have been bugging him to review ET for a long time.) Then there were a few others, should be on youtube.
If you're interested in Atari 2600 history, I also recommend the documentaries "Stella At 20" and the Stella at 20 part two. It was a 20th birthday party for the 2600 held at Noland Bushnells house (the first part, 2nd was additional people off site.) Lots of interesting insight into the a machine that changed the world.