[ZhL]

That's a good point. Thank you for the suggestion. I guess I'm a bit naive not thinking about this right away. :) Not sure if it is fair to only count retweets with 100-200 followers though.. Plenty of novice Twitter users don't have that amount of followers. What if I just charge a flat campaign fee? Or maybe a duration based fee? Need to think a bit more about it..

[ZhL]

Just wanted to share another thought about protection from bots. In my tests, I didn't get any retweets from bots or other fake accounts. I think it is because iOS promo codes don't have any tangible value to a bot operator. You cannot easily resell a promo code (AFAIK). And money is what they are after. I'm telling this from experience because I also tried to run a gift card giveaway from the same account I usually run promo code giveaways. I don't have many followers, just a bit shy of 200. The rules were similar: chance to win a $25 gift card for a retweet. I had about 20 retweets, only one of them was a real person. Everything else was retweeted by seemingly fake accounts, who followed my right before retweeting. I'm not saying bots will not be an issue. But I'd like to gather more data on this.