It would cost you only time if you did it yourself I have recently made a text based game with a battle system and know that it is time consuming. Your question is a bit open ended... it all depends what you want from the game.
My initial idea was to develope a mmorpg (like habbo.com but different concept). Can anyone make on of this? Thanks, SA
http://www.game-script.net I have been producing custom and pre-built mods and scripts for some time now. let me know if you need anything else. TJ