Another Hair Question

Has anyone ever had extensions put in their hair, either the permanent ones that last a few months or the clip on ones (human hair)? My hair is thin, fine and pin straight - and I want Jessica Simpson like waves for the wedding, and my hair will not get that way unless I add extensions. I am trying to decide between the two options, and I have no clue what I want to do. Thoughts, experiences, advise?

Thanks Ladies!!