market controls the price?

Every corrugated manufacturing company wants to maximize their production and profit. Fact is, no matter how good you are, there is another plant who does it faster, less expensive and makes more profit. New machinery, efficient logistics, buying raw materials - Ralf VanDenBerg writes a great article in SDCExec.com on Margin Killing Myths.

Corrugated prices on the rise. Will it stick?

http://www.convertingmagazine.com/article/446509-Paperboard_prices_keep_rising_flow_downstream.php

If you buy boxes your going to get a call regarding a price increase OR your supplier will just bill you and hope you don't notice the increase. You may have a contract that protects you against movements in paper, but those contracts are usually are for 10%. So be diligent and entertain quotes from other suppliers.