Buying followers is definitely a grey area. There's not an objective answer i could provide you. However, there is a stigma attached to purchased followers. An example including newt gingrich supposedly accused of purchasing followers.
I would highly recommend reviewing the terms of service for each social network. You run a risk of losing an account.
Reasons Against Buying a list
Like the other answers, I think that buying and/or selling followers is clearly unethical. I also think that it is prohibited by both Facebook and Twitter.
From Facebook's Terms of Service :
You will not use your personal profile for your own commercial gain (such as selling your status update to an advertiser).This would seem to cover selling "Likes" as well.
From Twitter's definition of spamming in the Twitter Rules, which are a part of their Terms of Service:
- If you have attempted to "sell" followers, particularly through tactics considered aggressive following or follower churn;
- Creating or purchasing accounts in order to gain followers;
- Using or promoting third-party sites that claim to get you more followers (such as follower trains, sites promising "more followers fast," or any other site that offers to automatically add followers to your account);
In my experience fan count is an irrelevant metric. Would you rather run Product A with 50,000 fans that are indifferent about your product (usually the case with bought fans), or Product B with 100 fans that absolutely love what you offer?