Make an easy 0.001btc just for going to
http://www.ViralNode.com and click on the button that says "Click here to become an active viral webnode" once clicked it will open a window from twitter asking your permission for Viral to occasionally post status updates on your account. Authorize it and then if successful you will see a "Viral metrics page" this let's you know it worked.
i think 0.001BTC is too low for this thing. if it is a tweet only maybe it is worth it.
You're absolutely right, if it was just post a tweet or retweet and follow, then the price was ok but to authorize an app to post as many tweets as it wants on your page is not worth it. I'd do it for 0.01 atleast.