The average price for 1,000 Twitter followers was $18; it s now down to $11. This suggests that the supply of Twitter accounts available for purchase has spiked and demand isn t quite as high right now. Barracuda Labs has been tracking the volume of fake accounts on Twitter as well as the prices that various sites and vendors charge for followers. On average each fake account is worth $0.011 or 1.1 cent per following, meaning each account has already made 66 cents in our study.
Source: https://threatpost.com/exploiting-the-twitter-underground-for-fun-and-profit/101138/