Buying your own script is a bad idea I think. It just seems like it would be at least as much work, if not more, as writing your own. You'd have to figure out where everything is, how it all works together, and then modify it for your own game. Seems like a lot of work to pay for. There are plenty of free scripts anyway. The only one I really like is ezRPG by Zeggy since it's so simple that it won't take long to start modifying it for your own needs. With ezRPG you basically just skip coding the boring stuff like registration (although you should beef up the registration later on anyway) and the index page and get right to coding content.