341669 server ip addresses

Hello, We have a dedicated server in wich we have some couple of ip addresses. The server provider, provides us with a certain maximim of ips that could not be exceeded in the server (30 for example). When we wanted to delete those ips and replace them wth new ip addresses our server provider did not gave us the possibility of getting new ip addresses. what we want is a consultancy: -regarding an external source where to buy ip addresses in bulk (sources that provide ip addreses for 1$/month each) -Show as in detail how to add those ip addresse to our server..... NB: -server without cpanel, only root access -ips used to send emails... -The external added ips should be like internal configured ip addresse -ability to not affect the other internal ips