In a word "consistency". More expensive carbon arrows have better quality control and are more consistent from arrow to arrow. If you take a cheap set of arrows and compare them in weight, straightness and spine with a more expensive arrow you will find the more expensive arrows probably have closer tolerances and you will have more good arrows out of the dozen.

If you don't shoot well enough to tell the difference then I guess it really doesn't matter. But don't expect to get any better with crappy equipment either. Especially when you are talking fixed broad heads.

My suggestion if you want bargain arrows is always to get aluminums. You still can't beat the quality control and tolerances for the money. I can't always see spending a lot of money on high grade aluminums when the cheaper ones are usually pretty close. However with carbons there is a difference for sure.

And don't believe that "they are straight or broke" crap either. It is not uncommon at all to have warped arrows right out of the box with some carbons.

They keep getting better every year though.

Paul