Most people want their own personal account. I am in the business for quite a while and I can tell you Twitter can be an effective tool as long as you know how to wheel it and not get red flagged or banned. As for the followers, many followers will get the exposure market but the secret is to make them pass it on...And that my friend is an art.
I tried selling tweets for a while. It was actually more trouble than it was worth. I do know that for my own sites, I do get a fair amount of visits when I tweet them out. Did try out several ad networks that pay per tweet, etc. Again, waste of my time. My take is this, bypass that idea and just be you on twitter and just tweet out your own sites.