A friend of mine has asked to consult with me on an affiliate site that he wishes to create. I've had my fair share with them but have never attempted to write one, although I think I've pretty much had a go at each separate part for different projects: Paypal API, time methods, user accounts etc etc.

I was wondering as it would probably be a substantial script to write, would it be worth him buying a script already avaliable? What are peoples experiences with these scripts?

Any feedback would be good, thanks.