Wow. Seeing as they have 50 ish followers and I have 15000 ish followers, whick is 300 times them, then according to that I should charge 3btc each. That's about 15-20 dollars depending on what mood mtgox is in. Wow.
Saying that, I would never charge more than 0.5 btc
slight difference is that they have 50 followers which specifically decided to follow a bitcoin-related advertising account.
i.e. they have quality (not saying yours aren't quality leads, but they probably wouldn't have the same level of 'bitcoin' focus)