I know what you are saying, but I would be leery of those "active followers" as they could be paid followers.  They can pay $70 to buy 50K followers and then turn around and sell tweets and retweets for $5.  They only need 14 customers to make their money back and then they are making profits.  Maybe some of them have legitimate followers, but I would be cautious that even legitimate followers may not be engaged followers.  However, I would lean more towards them paying for fake twitter accounts.

It is really easy to pick up new followers by using hashtags like #teamfollowback #TFBJP #follow4follow #FollowNGain, etc..  Sure you pick up free followers, that are legitimate, but these are not engaged followers (i.e. you may tweet about things that have little interest to them).

The only way to determine if the $5 gigs are good is to try it and see if their followers react in the manner you intended by initiating the tweets and retweets.