No you cannot get in trouble simply from what you posted without any other incident. High Times has been publishing the prices of drugs in different localities for 35 years without incident. That said, posting this on myspace isnt an extremely intelligent thing to do and can lead to legal problems by advertising your use to authorities which can provoke them to keep an eye on you. They either need to have the cannabis itself or have a sufficient evidence of you possessing cannabis to charge you, and even then they cannot be sure that you werent smoking oregano that you thought was cannabis because. In the unlikely event that they do ask you, just say that it was fictional or that you were playing around.
In the future exercise discretion and don't use alcohol or hard drugs, and never use cannabis outside of your home.