Rocky will be the first to tell you that there is a big difference in the construction of his 5 yard vs 8 yard kilts. If I'm not mistaken, his 5 yards kilts don't have the pleats cut out, a stabalizer, or any lining. There may be other less obvious construction differences that I'm not aware of also.

If budget is a non-issue (and if it is, I would just be patient and save longer) I would go for the 8 yard for sure.

Best of luck!