Not to mention you are looking in the wrong place. That site is the MOST expensive that you could possibly buy from.
As it has been said , to tank comes with 3:1 boxes Unless they are a special edition like the ones you are looking at.
It simply does not pay to buy one of these tanks, they are not kits, with the 3:1 boxes already installed. The extra price will kill you.
They are charging you to install them plus marking the price up too boot.