potential to earn $ on RT/follower train type accounts?

I have a couple of accounts growing in the RT/follower train area and I am wondering if these accounts have any potential to generate any kind of $.
Right off the bat I know that I'm not going to be making vasts amounts of money but there seems to be some potential. My friends seem to disagree with me.
At what level does one start to consider selling shoutouts or anything else related? One idea that keeps popping up in my head is to limit the amount of retweeting I allow to a specific niche and acquire several K
followers who are interested in that niche, wait a while for unfollowers to settle and get a stable number, and then market myself as a shoutout for people looking to grow in
said niche.

I know this isn't the ideal account type, but these are accounts with some age, that have been around for a good period of time (accounts are aged 4+ years)
Looking at my stats currently I am beginning to believe that a couples months worth of solid growth would put me in a position to sell shoutouts to a specific target audience
so I am wondering if anyone else has done something similar with these kinds of accounts, and how you went about it.

Any help would be appreciated

Thanks,
Stansy

Im interested to buy shotouts on twitter accs,add me on skype to talk about this.