It shouldn’t shock you that people participate in the buying and selling of Twitter followers – phantom accounts conjured out of thin air whose only real purpose is to serve as a number in a follower count and to sometimes act as a retweet factory. When people can’t gain the thousands of followers they want organically, through producing popular, timely content, they take the easy way.

But what should shock you is just how prevalent this practice really is.

Barracuda Labs just published the findings from a study they did concerning the “Twitter Underground Economy.”

Here’s how they set up the investigation:

As part of this study, beginning in May 2012, our team set up three Twitter accounts and purchased between 20,000 and 70,000 Twitter followers for each of them from eBay and another website searched from Google. After collecting these followers’ profiles via Twitter API, as well as additional information from eBay sellers and Google search results, we found many interesting highlights of this business, summarized as follows into 3 categories.

Those three categories are dealers (creators and sellers of fake accounts), abusers (buyers of fake followers), and the kae accounts themselves.

Here are some of the findings:

• Barracuda Labs found 20 eBay sellers and 58 websites devoted to the selling of fake Twitter followers.
• The average cost of buying 1,000 followers was $18.
• The average “Abuser” has 48,885 followers.
• The average fake account follows 1,799 people.
• 61% of the fake accounts identified were less than three months old
• Dealers are also making money selling retweets, for instance $5 for 2,000.

And though Twitter works to detect and suspend these fake accounts, there are ways around it.

“Dealers are controlling the following speed and total following number of these fake accounts to avoid being suspended by Twitter. Dealers can apply obscure techniques to make them hard to detect, e.g., randomly following some famous and some average people, or posting tweets grabbed from the Twitter stream, etc.,” said Barracuda Labs.

This isn’t the first time that we’ve heard that Twitter is riddled with fake and inactive accounts. One analyst recently said that Twitter had crossed the 500 million account mark – but not active users. A couple of months ago, Twitter CEO Dick Costolo announced 140 million active Twitter users. As you can see, there’s a discrepancy here between active users and total accounts. A big one.

Gaining influence on Twitter is all about gaining followers. And as long as this is the case (which it always will be), people we cheat the system. But it has to be a concern for Twitter, if so many of their users aren’t actually real users. I mean, what does it say to an advertiser when the creation and selling of fake accounts is so rampant across the network?

Check out their infographic below, which contains some specific information on a certain Presidential candidate’s Twitter follower problems.