special message part for private members

Hello, We have general message system, we will make it better later on. Until that time - i would like to close message system to the free members and non-members What i want? 1- any free member and non- members click it just show them note that message system available just for paid members. 2- I will have 5 paid membership, so they should send messages without any problem. BRONZE SILVER GOLD PLATINUM DIAMOND So i need something simple, my budget is low!!!