How much does instant messaging cost for the Samsung Eternity?

I want to get internet on my Samsung Eternity, but I was wondering how much instant messaging cost per month, because if it's cheaper than the internet ($10 a month) I might just get the instant messaging.How much does instant messaging cost for the Samsung Eternity?Unlimited messaging is 20 dollars a month for 15 a month you get 1500 messages and for 5 a month you get 200 messages. Hope this is what you were looking for.