Sad, but I'm not surprised. Some people are greedy and would sell their own mothers to make a buck. But what's even worse, is even though we may think it's stupid for someone to sell a regular beta key, you KNOW somebody is going to buy it.
The real reason it's hard to get beta keys is because everyone is trying to get a beta key, what they do with it afterwards doesn't have any impact on how we obtain them. Besides, if you're talking about the twitter and facebook beta keys this guy isn't even selling one of those (because that would be impossible).