It's no lie that arrows are expensive. A single Rating 10 arrow costs as much as 10 rounds of regular ammunition, and if you add any of the optional heads the cost can easily exceed that of assault cannon rounds (40¥ per round).
A Rating 5 arrow costs 10¥, so adding a barbed head doubles the price while adding an incendiary head increases the price by a factor of five.
The increase to cost is for the arrow.. Most of the other arrows have a 2gp cost increase. The sudden increase for the Rating is because the shaft now has a higher rating than the arrow head.
The only place this doesn't make sense is the static shaft, which is including the standard arrow, plus the shaft, plus the arrow head.
Care to elaborate? I don't quite know what you're saying here.
The Static Shaft represents an additional cost over the normal arrow (23¥ per rating), and as Imveros points out none of the arrowheads actually have a rating at all.