Buying twitter followers has been popular for quite a while now, but let me tell you that when it comes to buying twitter followers, you're most likely not getting real followers, if you are, they're just trying to grow their follower list as well.
All of the services I've used only give me followers who never interact with me. If you want to get business, or get traffic from these followers, you need interaction, they need to be real people, if they are not, it's just a number of followers rather than a number of users.